Kingdom of Hungary (Early Medieval)

Stephen was crowned the first king of Hungary. He consolidated his rule through a series of wars against semi-independent local rulers, including his maternal uncle, Gyula, and the powerful tribal chief, Ajtony.

Stephen encouraged the spread of Christianity by meting out severe punishments for ignoring Christian customs. His system of local administration was based on counties organized around fortresses and administered by royal officials. Hungary enjoyed a lasting period of peace during his reign, and became a preferred route for pilgrims and merchants traveling between Western Europe, the Holy Land and Constantinople.

He survived all of his children, dying on 15 August 1038 aged 62 or 63. He was buried in his new basilica, built in Székesfehérvár and dedicated to the Holy Virgin. His death was followed by civil wars which lasted for decades. 

Many Hungarian lords refused to accept Stephen's suzerainty even after his coronation. The new King first turned against his own uncle, Gyula the Younger, whose realm "was most wide and rich", according to the Illuminated Chronicle. Stephen invaded Transylvania and seized Gyula and his family around 1002 or in 1003. The contemporary Annals of Hildesheim adds that Stephen converted his uncle's "country to the Christian faith by force" after its conquest.

Stephen developed a state similar to the monarchies of contemporary Western Europe. Counties, the basic units of administration, were districts organized around fortresses and headed by royal officials known as ispáns, or counts. Most of the early medieval fortresses were made of earth and timber. Stephen founded dioceses and at least one archbishopric, and established Benedictine monasteries. He prescribed that every tenth village was to build a parish church. The earliest churches were simple wood constructions, but the royal basilica at Székesfehérvár was built in Romanesque style. With the introduction of the Catholic church hierarchy, Latin emerged as the dominant language of ecclesiastic life and state administration, although some royal charters were likely written in Greek.The bishops were required to supply the local clergy with liturgical books, and the kings regularly donated codices to monasteries. 

The Illuminated Chronicle narrates that Stephen "led his army against Kean, Duke of the Bulgarians and Slavs whose lands are by their natural position most strongly fortified" following the occupation of Gyula's country. According to a number of historians, including Zoltán Lenkey and Gábor Thoroczkay, Kean was the head of a small state located in the southern parts of Transylvania and Stephen occupied his country around 1003. Other historians, including Györffy, say that the chronicle's report preserved the memory of Stephen's campaign against Bulgaria in the late 1010s.

Stephen's brother-in-law, Henry II, became King of Germany in 1002 and Holy Roman Emperor in 1013. Their friendly relationship ensured that the western borders of Hungary experienced a period of peace in the first decades of the 11th century. Even when Henry II's discontented brother, Bruno, sought refuge in Hungary in 1004, Stephen preserved the peace with Germany and negotiated a settlement between his two brothers-in-law. Around 1009, he gave his younger sister in marriage to Otto Orseolo, Doge of Venice (r. 1008–1026), a close ally of the Byzantine Emperor, Basil II (r. 976–1025), which suggests that Hungary's relationship with the Byzantine Empire was also peaceful. 

On the other hand, the alliance between Hungary and the Holy Roman Empire brought her into a war with Poland lasting from around 1014 until 1018. The Poles occupied the Hungarian posts along the river Morava. Györffy and Kristó write that a Pecheneg incursion into Transylvania, the memory of which has been preserved in Stephen's legends, also took place in this period, because the Pechenegs were close allies of the Polish duke's brother-in-law, Grand Prince Sviatopolk I of Kiev (r. 1015–1019). Poland and the Holy Roman Empire concluded the Peace of Bautzen in January 1018.

Stephen's views on state administration were summarized around 1015 in a mirror for princes known as Admonitions. Stating that "the country that has only one language and one custom is weak and fragile", he emphasized the advantages of the arrival of foreigners, or "guests". His laws were aimed at the adoption, even by force, of a Christian way of life. He especially protected Christian marriage against polygamy and other traditional customs. Decorated belts and other items of pagan fashion also disappeared. Commoners started to wear long woolen coats, but wealthy men persisted in wearing their silk kaftans decorated with furs.

According to Leodvin, the first known Bishop of Bihar, Stephen allied with the Byzantine Empire and led a military expedition to assist them against "barbarians" in the Balkan Peninsula. The Byzantine and Hungarian troops jointly took "Cesaries" which Györffy identifies as the present-day town of Ohrid. Leodvin's report suggests that Stephen joined the Byzantines in the war ending with their conquest of Bulgaria in 1018. However, the exact date of his expedition is uncertain. Györffy argues that it was only in the last year of the war that Stephen led his troops against the Bulgarians. This conquest ended the First Bulgarian Empire.

Bishop Leodvin wrote that Stephen collected relics of a number of saints in "Cesaries" during his campaign in the Balkans, including Saint George and Saint Nicholas. He donated them to his new triple-naved basilica dedicated to the Holy Virgin in Székesfehérvár, where he also set up a cathedral chapter and his new capital. His decision was influenced by the opening, in 1018 or 1019, of a new pilgrimage route that bypassed his old capital, Esztergom.

The new route connected Western Europe and the Holy Land through Hungary. Stephen often met the pilgrims, contributing to the spread of his fame throughout Europe. Abbot Odilo of Cluny, for example, wrote in a letter to Stephen that "those who have returned from the shrine of our Lord" testify to the king's passion "towards the honour of our divine religion". Stephen also established four hostels for pilgrims in Constantinople, Jerusalem, Ravenna and Rome.

In addition to pilgrims, merchants often used the safe route across Hungary when travelling between Constantinople and Western Europe. Stephen's legends refer to 60 wealthy Pechenegs who travelled to Hungary, but were attacked by Hungarian border guards. The king sentenced his soldiers to death in order to demonstrate his determination to preserve internal peace.

Stephen's brother-in-law, Emperor Henry, died on 13 July 1024. He was succeeded by a distant relative, Conrad II (r. 1024–1039), who adopted an offensive foreign policy. Conrad II expelled Doge Otto Orseolo—the husband of Stephen's sister—from Venice in 1026.

Emperor Conrad personally led his armies to Hungary in June 1030 and plundered the lands west of the River Rába. However, according to the Annals of Niederalteich, the emperor, suffering from consequences of the scorched earth tactics used by the Hungarian army, returned to Germany "without an army and without achieving anything, because the army was threatened by starvation and was captured by the Hungarians at Vienna". Peace was restored after Conrad had ceded the lands between the rivers Lajta and Fischa to Hungary in the summer of 1031.

Peter Orseolo, or Peter the Venetian, was King of Hungary twice. He first succeeded his uncle, King Stephen I, in 1038. His favoritism towards his foreign courtiers caused an uprising which ended with his 1041 deposition. Peter was restored in 1044 by Henry III, Holy Roman Emperor. He accepted the Emperor's suzerainty during his second reign, which ended in 1046 after a pagan uprising. Hungarian chronicles are unanimous that Peter was executed by order of his successor, Andrew I, but the chronicler Cosmas of Prague's reference to his alleged marriage around 1055 suggests that he may also have survived his second deposition.

Peter Orseolo, who had been deposed by Samuel Aba in 1041, returned with the assistance of Emperor Henry III, and invaded Hungary in June 1044. His force was small and the Hungarian army of Samuel Aba was large. However, there was disaffection in the Hungarian ranks and the army quickly fell apart in the face of the German cavalry. Samuel fled the field, but was captured and killed. Peter was reinstalled as king at Székesfehérvár and did homage for his kingdom to Henry. The leading magnates and the less important nobles all came to Henry to make oaths of fidelity and vassalage. Hungary was made a vassal of the Holy Roman Empire, though it was not to remain so for long.

The Battle of Ménfő was an important battle in the early history of the Kingdom of Hungary. Fought in 1044 at Ménfő, near Győr, between an army of mostly Germans and Hungarians (Magyars), it was a victory for the Germans and thus for Westernising influences in Hungary.

During this rebellion, a pagan noble named Vata (or Vatha) gained power over a group of rebels who wished to abolish Christian rule and revert to paganism. According to legend Vata shaved his head in the pagan fashion, leaving three braids remaining, and declared war on the Christians. A slaughter of priests and Christians by Vata's mob ensued.

King Peter is said to have fled towards Székesfehérvár, where he was killed by the rebellious townspeople, and András, as the oldest brother, pronounced himself king. As András and Levente's men moved towards Pest, the bishops Gerard, Besztrik, Buldi and Beneta gathered to greet them.

In Pest, on September 24, the bishops were attacked by Vata's mob, who began stoning the bishops. Buldi was stoned to death. As the pagans threw rocks at him, Gellért repeatedly made the sign of the cross, which further infuriated the pagans.

The Vatha uprising marked the last major attempt at stopping Christian rule in Hungary. While Andrew had received assistance from pagans in his rise to the throne, he had no plans to abolish Christianity in the kingdom. Once in power he distanced himself from Vatha and the pagans. However, they were not punished for their actions.

Andrew I the White was King of Hungary from 1046 to 1060. He descended from a younger branch of the Árpád dynasty. After spending fifteen years in exile, he ascended the throne during an extensive revolt of the pagan Hungarians. He strengthened the position of Christianity in the Kingdom of Hungary and successfully defended its independence against the Holy Roman Empire.

His efforts to ensure the succession of his son, Solomon, resulted in the open revolt of his brother, Béla. Béla dethroned Andrew by force in 1060. Andrew suffered severe injuries during the fighting and died before his brother was crowned king.

Skirmishes on the frontier between Hungary and the Holy Roman Empire first occurred in 1050. Emperor Henry invaded Hungary in August 1051, but Andrew and Béla successfully applied scorched earth tactics against the imperial troops and forced them to withdraw. Legend says that the Vértes Hills near Székesfehérvár were named after the armours—vért in Hungarian—which were discarded by the retreating German soldiers.

Andrew initiated new peace negotiations with the emperor and promised to pay an annual tribute, but his offers were refused. Next summer, the emperor returned to Hungary and laid siege to Pressburg (Bratislava, Slovakia). Zotmund, "a most skilful swimmer" scuttled the emperor's ships. After Pope Leo IX mediated a peace treaty, the emperor lifted the siege and withdrew from Hungary. Andrew soon refused to fulfill his promises made under duress, and even allied with Conrad I, Duke of Bavaria, a prominent opponent of Emperor Henry III.

The East–West Schism (also known as the Great Schism or Schism of 1054) was the break of communion which occurred in the 11th century between the Western and Eastern churches. Immediately following the schism, it is estimated that Eastern Christianity comprised a slim majority of Christians worldwide, with the majority of remaining Christians being Western. The schism was the culmination of theological and political differences which had developed during the preceding centuries between Eastern and Western Christianity.

In the following years, Solomon and his cousins jointly fought against the Czechs, the Cumans and other enemies of the kingdom. Their relationship deteriorated in the early 1070s and Géza rebelled against him. Solomon could only maintain his rule in a small zone along the western frontiers of Hungary after his defeat in the Battle of Mogyoród on 14 March 1074. He officially abdicated in 1081, but was arrested for conspiring against Géza's brother and successor, Ladislaus.

Solomon was set free during the canonization process of the first king of Hungary, Stephen I, in 1083. In an attempt to regain his crown, Solomon allied with the Pechenegs, but King Ladislaus defeated their invading troops. According to a nearly contemporaneous source, Solomon died on a plundering raid in the Byzantine Empire. Later legends say that he survived and died as a saintly hermit in Pula (Croatia).

The Battle of Kerlés (Hungarian: kerlési csata) or Battle of Chiraleș, also known as the Battle of Cserhalom, was an engagement between an army of Pechenegs and Ouzes commanded by Osul and the troops of King Solomon of Hungary and his cousins, Dukes Géza and Ladislaus, in Transylvania in 1068. The Pechenegs had been the dominant power of the westernmost regions of the Eurasian steppes since around 895. However, large Pecheneg groups moved to the Balkan Peninsula at the same time as the westward migration of the Ouzes and Cumans in the 1040s. The first recorded Pecheneg invasion of Transylvania occurred during the reign of Stephen I of Hungary (r. 997–1038).

In 1068, the invaders broke into Transylvania through the passes of the Carpathian Mountains. Archaeological finds suggest that they destroyed at least three fortresses made of earth and timber, including the ones at Doboka (now Dăbâca in Romania) and Sajósárvár (present-day Șirioara). They also made a plundering raid in the Nyírség region, to the west of Transylvania. After taking much booty, they planned to leave Hungary, but the Hungarians ambushed and annihilated them at a hill near Doboka. According to a popular legend, a "Cuman" warrior tried to escape from the battlefield, taking a Hungarian girl, but Duke Ladislaus defeated and killed him in single combat.

Pecheneg troops pillaged Syrmia (now in Serbia) in 1071. As the king and the duke suspected that the soldiers of the Byzantine garrison at Belgrade incited the marauders against Hungary, they decided to attack the fortress. The Hungarian army crossed the river Sava, although the Byzantines "blew sulphurous fires by means of machines" against their boats. The Hungarians took Belgrade after a siege of three months. However, the Byzantine commander, Niketas, surrendered the fortress to Duke Géza instead of the king; he knew that Solomon "was a hard man and that in all things he listened to the vile counsels of Count Vid, who was detestable in the eyes both of God and men", according to the Illuminated Chronicle.

Division of the war-booty caused a new conflict between Solomon and his cousin, because the king granted only a quarter of the booty to the duke, who claimed its third part. Thereafter the duke negotiated with the Byzantine Emperor's envoys and set all the Byzantine captives free without the king's consent. The conflict was further sharpened by Count Vid; the Illuminated Chronicle narrates how the count incited the young monarch against his cousins by saying that as "two sharp swords cannot be kept in the same scabbard", so the king and the duke "cannot reign together in the same kingdom". 

After a series of campaigns directed against the Byzantine Empire, which were led by Duke Géza and Ladislaus, Solomon grew bitter and felt unappreciated because of their success on the field. This provoked numerous actions of the king on their expense and was eventually followed up by attempts of murder. The princes decided to settle this in a battle and it ended favorably for them thanks to the assistance of Otto I of Brno and his forces, who was married to Euphemia, one of the sisters of Ladislaus and Géza.

The injured king fled to Germany soon after the battle and there he aimed to regain the crown with the help of his son-in-law. The outcome of this battle overjoyed all of the nation, since it was regarded as a decisive victory for Hungary's statehood.

Thereafter, Solomon preserved only Moson and the nearby Pressburg (Bratislava, Slovakia). Other parts of the kingdom accepted the rule of Géza, who had been proclaimed king after his victory.

Géza died in 1077, and his supporters made Ladislaus king. Solomon resisted Ladislaus with assistance from King Henry IV of Germany. Ladislaus supported Henry IV's opponents during the Investiture Controversy. In 1081, Solomon abdicated and acknowledged Ladislaus's reign, but he conspired to regain the royal crown and Ladislaus imprisoned him. Ladislaus canonized the first Hungarian saints (including his distant relatives, King Stephen I and Duke Emeric) in 1085. He set Solomon free during the canonization ceremony.

After a series of civil wars, Ladislaus's main focus was the restoration of public safety. He introduced severe legislation, punishing those who violated property rights with death or mutilation. He occupied almost all Croatia in 1091, which marked the beginning of an expansion period for the medieval Kingdom of Hungary. Ladislaus's victories over the Pechenegs and Cumans ensured the security of his kingdom's eastern borders for about 150 years. His relationship with the Holy See deteriorated during the last years of his reign, as the popes claimed that Croatia was their fief, but Ladislaus denied their claims.

Stephen II, King of Croatia, died at the beginning of 1091, without leaving an heir. Since there was no living male member of the House of Trpimirović, civil war broke out shortly afterward. The widow of the late King Zvonimir, Helen, tried to keep power in Croatia during the succession crisis. Some Croatian nobles around Helen, possibly the Gusić family and/or Viniha from Lapčan family, contesting the succession after the death of Zvonimir, asked King Ladislaus I to help Helen and offered him the Croatian throne, which was seen as his by right of inheritance. 

According to some sources, several Dalmatian cities also asked King Ladislaus for assistance, and Petar Gusić with Petar de genere Cacautonem presented themselves as "White Croats" (Creates Albi), on his court. Thus the campaign launched by Ladislaus was not purely a foreign aggression nor did he appear on the Croatian throne as a conqueror, but rather as hereditary successor. In 1091 Ladislaus crossed the Drava river and conquered the entire province of Slavonia without encountering opposition, but his campaign was halted near the Forest Mountain (Mount Gvozd). Since the Croatian nobles were divided, Ladislaus had some success in his campaign, yet he wasn't able to establish his control over the entirety of Croatia, although the exact extent of his conquest is not known. 

At this time the Kingdom of Hungary was attacked by the Cumans, who were likely sent by Byzantium, so Ladislaus was forced to retreat from his campaign in Croatia. Ladislaus appointed his nephew Prince Álmos to administer the controlled area of Croatia, established the Diocese of Zagreb as a symbol of his new authority and went back to Hungary.

The Cumans invaded and plundered the eastern part of the kingdom in 1091. The invading Cumans were leading by chieftain Kapolcs, they broke first in Transylvania, then the territory between the Danube and Tisza rivers. The Cumans tried to leave Hungary with their huge booty and prisoners, but King Ladislaus reached and defeated them near the Temes river. Ladislaus offered the Christianity for the Cuman survivors, the majority of them accepted, thus the king settled them in Jászság. The rumor of the losing battle reached the Cuman camp, the Cumans threatened King Ladislaus with revenge and demanded to free the Cuman prisoners. King Ladislaus marched to the Hungarian border to prevent the next invasion. The two armies clashed near Severin, the Hungarian army was victorious, King Ladislaus killed Ákos, the Cuman chieftain. Makk argues that the Byzantines persuaded them to attack Hungary, while the Illuminated Chronicle states that the Cumans were incited by the "Ruthenians". In retaliation, the chronicle continues, Ladislaus invaded the neighboring Rus' principalities, forcing the "Ruthenians" to ask "for mercy" and to promise "that they would be faithful to him in all things". No Rus' chronicle documents Ladislaus's military action.

In the year of Coloman's coronation, at least five large groups of crusaders arrived in Hungary on their way to the Holy Land. He annihilated the bands who were entering his kingdom unauthorized or pillaging the countryside, but the main crusader army crossed Hungary without incident. He invaded Croatia in 1097, defeating its last native king Petar Svačić. Consequently, he was crowned king of Croatia in 1102. For centuries thereafter, the Hungarian monarchs were also the kings of Croatia.

Coloman had to face his brother's attempts to dethrone him throughout his life; Álmos devised plots to overthrow him on at least five occasions. In retaliation, he seized his brother's duchy in 1107 or 1108 and had Álmos and Álmos' son Béla blinded in about 1114.

Shortly after his coronation, Coloman had to face problems that the armies of the First Crusade caused while passing through Hungary. For decades, Hungary had been able to supply a significant number of Western European pilgrims with food during their journey to the Holy Land, but the movement of tens of thousands of crusaders across the country endangered the natives' subsistence. The first group of crusaders, led by Walter Sans Avoir, reached the frontier in early May 1096. Coloman received them in a friendly way and allowed them into the kingdom. He also authorized them to buy food in the markets, although harvest had not started yet. They proceeded through Hungary without any major conflicts.

The next arrivals, headed by Peter the Hermit, arrived in late May or early June. Coloman permitted them to enter Hungary only after Peter pledged that he would prevent them from pillaging the countryside. According to Guibert of Nogent's records, Peter could not keep his promise: the crusaders "burned the public granaries ..., raped virgins, dishonored many marriage beds by carrying off many women", although "the Hungarians, as Christians to Christians, had generously offered everything for sale" to them.

A third band of crusaders reached Nyitra (Nitra, Slovakia) and began plundering the region. These were soon routed by the locals. A fourth army came to Moson in the middle of June. Coloman did not allow them to leave the region, either because he had learnt of their troublesome behavior during their journey, or he had realized that their movement across Hungary could jeopardize the stability of the local economy. To seize food and wine, the crusaders made frequent pillaging raids against the nearby settlements. Coloman decided to attack them, but the commanders of the army convinced him to persuade the crusaders to surrender their weapons and money, promising them that they would be supplied with food during their journey. After the crusaders were disarmed, Coloman's troops attacked and massacred them near Pannonhalma in early July.

Alarmed by these incidents, Coloman forbade the crusaders who arrived under the leadership of Count Emicho in the middle of July to enter Hungary. Ignoring the king's order, they broke through the defensive lines and laid siege to Moson. Their catapults destroyed the walls in two places, enabling them to storm into the fortress on 15 August. Coloman made preparations to flee to Rus', fearing that the crusaders would occupy the whole country. However, for no apparent reason, a panic broke out among the attackers that enabled the garrison to carry out a sortie and rout them. Modern scholars agree that rumours about the sudden arrival of Coloman's army frightened the crusaders off from the fortress. According to Albert of Aix, contemporaneous Christians thought that Emicho's defeat was a punishment that God inflicted on the pilgrims because they had massacred many Jews "rather from greed for their money than for divine justice".

The first crusader army organized by the Holy See reached the borders of Hungary in September 1096. It was led by Godfrey of Bouillon, Duke of Lower Lorraine. Godfrey sent a knight who had already been known to Coloman to start negotiations about the crusaders' entry into Hungary. Eight days later, Coloman agreed to meet with Godfrey in Sopron. The king allowed the crusaders to march through his kingdom but stipulated that Godfrey's younger brother Baldwin and his family should stay with him as hostages. The crusaders passed through Hungary peacefully along the right bank of the Danube; Coloman and his army followed them on the left bank. He only released his hostages after all the crusaders had crossed the river Sava, which marked the kingdom's southern frontier. The uneventful march of the main crusader army across Hungary established Coloman's good reputation throughout Europe.

The contemporaneous Cosmas of Prague wrote that "some of the Jews" who had been persecuted by the crusaders in Bohemia arrived in Hungary and "secretly took their wealth away with them". Although Cosmas does not specify their number, László Mezey and other historians say that the Jews represented a large influx. Coloman issued a number of decrees and separate statutes—Capitula de Iudeis—regulating the position of Jews in Hungary. For instance, he forbade them from holding Christian slaves and residing "outside episcopal sees". Historian Nora Berend writes that the "defence of purity of Christians by interdictions against mingling with Jews plays a very minor role" in Coloman's legislation in comparison with late 12th-century canon law. Whereas he did not try to convert the Jews, he issued decrees aimed at the conversion of his Muslim subjects. For instance, he prescribed that if a Muslim "has a guest, or anyone invited to dinner, both he and his table companions shall eat only pork for meat" in order to prevent Muslims from observing their dietary laws.

Coloman invaded Croatia in 1097. Ladislaus I had already occupied most of the country, but Petar Svačić, the last native king of Croatia, resisted him in the Kapela Mountains. Petar Svačić died fighting against Coloman's army in the Battle of Gvozd Mountain. The Hungarian troops reached the Adriatic Sea and occupied Biograd na Moru, an important port. Threatened by the advance of Coloman's army, the citizens of the towns of Trogir and Split swore fidelity to the doge of Venice, Vitale Michiel, who had sailed to Dalmatia. Having no fleet, Coloman sent envoys with a letter to the doge to "remove all the former misunderstandings concerning what is due to one of us or the other by right of our predecessors". Their agreement of 1098—the so-called Conventio Amicitiae—determined the spheres of interest of each party by allotting the coastal regions of Croatia to Hungary and Dalmatia to the Republic of Venice.

In an attempt to win the crown of the Kingdom of Croatia, the Hungarian army crossed the River Drava and invaded Croatian territory, trying to reach the Adriatic coast. A local lord, Petar Svačić, then moved from his residency at Knin castle in an attempt to defend the kingdom from the Hungarians. Petar and his army moved north to meet the advancing Hungarians.

The Battle of Gvozd Mountain took place in the year 1097 and was fought between the army of Petar Svačić and King Coloman I of Hungary. It was a decisive Hungarian victory, which ended the War of the Croatian Succession and served as a turning point in Croatian history.

The outcome of the battle was disastrous for Petar Svačić's army and country because it marked the official end of a native dynasty ruling in Croatia. The winner of the battle, King Coloman of Hungary created a personal union between the kingdoms of Hungary and Croatia (allegedly signing the Pacta conventa). He was then crowned as King of Croatia in the Croatian capital Biograd on the Adriatic coast in 1102. Until the end of the World War I in 1918, the two crowns were united in personal union.

Coloman was crowned king of Croatia in Biograd na Moru in 1102. In the 13th century, Thomas the Archdeacon wrote that the union of Croatia and Hungary was the consequence of conquest. However, the late 14th-century Pacta conventa narrates that he was only crowned after he had reached an agreement with twelve leading Croatian noblemen, because the Croats were preparing to defend their kingdom against him by force. Whether this document is a forgery or an authentic source is a subject of scholarly debate.

In an attempt to prevent an alliance between Coloman and Bohemond I of Antioch, the Byzantine Emperor Alexios I Komnenos arranged a marriage between his son and heir, John, and Coloman's cousin, Piroska, in 1104 or 1105. The alliance with the Byzantine Empire also enabled Coloman to invade Dalmatia in 1105.According to the Life of the blessed John of Trogir, he personally commanded his troops besieging Zadar, the most influential among the Dalmatian towns. The siege lasted until Bishop John of Trogir negotiated a treaty between Coloman and the citizens who accepted the king's suzerainty. The town of Split likewise surrendered after a short siege, but two other Dalmatian towns—Trogir and Šibenik—capitulated without resistance. The Life of St Christopher the Martyr also says that a Hungarian fleet subjugated the islands of the Gulf of Kvarner, including Brač, Cres, Krk, and Rab. Thomas the Archdeacon narrates that Coloman granted each Dalmatian town its own "charter of liberties" to secure their loyalty. These liberties included the citizens' right to freely elect the bishop of their town and their exemption from any tribute payable to the monarch. Following his conquest of Dalmatia, Coloman assumed a new title—"King of Hungary, Croatia and Dalmatia"—which was first recorded in 1108.

The fleet of Venice, commanded by Doge Ordelafo Faliero, invaded Dalmatia in August 1115. The Venetians occupied the Dalmatian islands and some of the coastal cities but could not take Zadar and Biograd na Moru.

Stephen II, King of Hungary and Croatia, ruled from 1116 until 1131. His father, King Coloman, had him crowned as a child, thus denying the crown to his uncle Álmos. In the first year of his reign, Venice occupied Dalmatia and Stephen never restored his rule in that province. His reign was characterized by frequent wars with neighbouring countries.

The Battle of Olšava was an engagement of Bohemian and Hungarian troops near the Olšava River along the frontier of the two realms in May 1116. The event started as a peaceful meeting between the young Stephen II of Hungary and Vladislaus I of Bohemia, according to Hungarian chronicles. The Czech Cosmas of Prague wrote that the Hungarians came to the border to provocate a war.

Doge Ordelafo Faliero, who had conquered an island in the Gulf of Kvarner during the last year of Coloman's reign, returned to Dalmatia at the head of the Venetian fleet in May 1116. On 15 July, he vanquished the Hungarian troops which had arrived to relieve Zadar. Thereafter all towns — including Biograd na Moru, Šibenik, Split, and Trogir — surrendered to Venice, terminating Stephen II's suzerainty along the coastline of the Adriatic Sea. However, in either 1117 or 1118, the Hungarian troops were able to defeat the Venetians, during which Ordelafo Faliero himself died at a battle near Zadar, enabling Biograd na Moru, Split, and Trogir to rejoin the sovereignty of the Hungarian monarch. However, the new doge, Domenico Michele, invaded and reconquered all Dalmatia. A five-year truce, which was concluded in 1117 or 1118, confirmed the status quo: the seizure of Dalmatia by Venice.

Stephen married a daughter of Robert I of Capua, in the early 1120s. Historian Paul Stephenson wrote that Stephen's marriage alliance with the Normans of Southern Italy "... must have been partly directed against the Venetians." The Norman princes of Capua had been the pope's staunch supporters during the Investiture Controversy, suggesting that his marriage also continued his father's pro-Papal foreign policy. According to Włodzimierz Dworzaczek, Stephen in 1121 married Adelhaid, daughter of Heinrich, burgrave of Regensburg.

In 1123, the young king Stephen II launched a military expedition against the Principality of Volhynia in order to assist its expelled prince, Iaroslav Sviatopolkovich, regain his throne. Even though Sviatopolchich was assassinated at the beginning of the siege of his former seat, Volodymyr-Volynskyi, Stephen decided to continue the war. However, according to the Illuminated Chronicle, his commanders threatened to dethrone him if he continued the aggression, forcing Stephen to lift the siege and return to Hungary.

Cosma, of the line of Paznan, stood up before the King and said: "Lord, what is this thing which you are doing? If with the death of a multitude of your soldiers you take the castle, whom will you appoint as its lord? If you choose one among your nobles, he will not remain here. Or do you wish to abandon your kingdom and yourself have the dukedom? We barons will not storm the castle. If you wish to storm it, storm it alone. We are returning to Hungary and we will choose for ourselves a king." Then by order of the nobles the heralds announced throughout the camp that the Hungarians should return as speedily as possible to Hungary. When the King thus saw himself justly deprived of the help of his people, he returned to Hungary.

— The Hungarian Illuminated Chronicle

Taking advantage of the absence of the Venetian fleet from the Adriatic Sea because of a naval expedition in the Levant, Stephen invaded Dalmatia in the first half of 1124. His charter confirming the liberation of Split and Trogir in July 1124 is evidence that the central regions of Dalmatia returned to his rule. However, upon the return of the Venetian armada the Dalmatian towns once again surrendered, one after another. According to the Historia Ducum Veneticorum, only the citizens of Biograd na Moru "... dared resist the doge and his army ...", but "... their city was razed to its foundations."

According to the Byzantine chronicler Niketas Choniates, the citizens of the Byzantine town Braničevo "attacked and plundered the Hungarians who had come to" the Byzantine Empire "to trade, perpetrating the worst crimes against them." In retaliation, Stephen decided to wage war against the Byzantine Empire.

Stephen broke into the Byzantine Empire in the summer. His troops sacked Belgrade, Braničevo and Niš, and plundered the regions around Serdica (Sofia, Bulgaria) and Philippopolis (Plovdiv, Bulgaria), before returning to Hungary. In response, Emperor John II marched against Hungary in 1128, where he defeated the royal troops in a battle at Haram, and "captured Frangochorion, the richest land in Hungary" (now in Serbia). Stephen was unable to participate in the fighting because "he happened to be sickly in body and was recuperating someplace in the midst of his land", according to John Kinnamos. The Illuminated Chronicle said that his illness was so serious that "all expected his death." The chronicle added that "traitors" went so far as to elect two kings, the "Counts Bors and Ivan". Upon regaining his health, Stephen had Ivan executed and expelled Bors from his kingdom.

John Kinnamos wrote of a second campaign by Stephen against the Byzantine Empire. The Hungarian troops, supported by Czech reinforcements under the command of Duke Vaclav of Olomouc, took Braničevo by storm and destroyed its fortress. Byzantine Emperor John II Komnenos was forced to retreat and sue for peace. Historian Ferenc Makk writes that the resulting peace treaty was signed in October 1129.

The Battle of Haram or Chramon was fought between the forces of King Stephen II (r. 1116–1131) of Hungary and Emperor John II Komnenos (r. 1118–1143) of the Byzantine Empire in the year 1128, or possibly earlier – in 1125 (the chronology is uncertain), in what is now Serbia, and resulted in a major defeat for the Hungarians.

Béla the Blind was King of Hungary and Croatia from 1131 to 1141. He was blinded along with his rebellious father Álmos on the order of Álmos's brother, King Coloman of Hungary. Béla grew up in monasteries during the reign of Coloman's son Stephen II. The childless king arranged Béla's marriage with Helena of Rascia, who would become her husband's co-ruler throughout his reign.

Béla was crowned king at least two months after the death of Stephen II, implying that his accession to the throne did not happen without opposition. Two violent purges were carried out among the partisans of his predecessors to strengthen Béla's rule. King Coloman's alleged son Boris tried to dethrone Béla but the king and his allies defeated the pretender's troops in 1132. In the second half of Béla's reign, Hungary adopted an active foreign policy. Bosnia and Split seem to have accepted Béla's suzerainty around 1136.

Béla's blindness prevented him from administering his kingdom without assistance. He put his trust in his wife and her brother Beloš. Both royal and private charters from Béla's reign emphasize Queen Helena's pre-eminent role in the decision-making process, proving that the king regarded his wife as his co-ruler. According to the Illuminated Chronicle, at "an assembly of the realm near Arad" in early to mid-1131, Queen Helena ordered the slaughter of all noblemen who were accused of having suggested the blinding of her husband to King Coloman. Béla distributed the goods of the executed magnates between the newly established Arad Chapter and the early 11th-century Óbuda Chapter.

Béla's was on good terms with the Holy Roman Empire, jeopardizing the interests of Boleslaw III of Poland who had been warring with the empire. The Polish monarch decided to support a pretender to the Hungarian crown named Boris. After Boris arrived in Poland, a number of Hungarian noblemen joined him.

Accompanied by Polish and Rus' reinforcements, Boris broke into Hungary in mid-1132. Béla entered into an alliance with Leopold III, Margrave of Austria. Before launching a counter-attack against Boris, Béla convoked a council on the river Sajó. The Illuminated Chronicle relates that the King asked "the eminent men of Hungary" who were present if they knew whether Boris "was a bastard or the son of King Coloman". The King's partisans attacked and murdered all those who proved to be "disloyal and divided in their minds" during the meeting.

Béla tried to persuade the Polish monarch to stop supporting the pretender. However, Boleslaw remained loyal to Boris. In the decisive battle, which was fought on the river Sajó on 22 July 1132, the Hungarian and Austrian troops defeated Boris and his allies.

Hungary adopted an expansionist policy after Boris's attempts to dethrone Béla. The chronicler Thomas the Archdeacon relates that Gaudius, who became Archbishop of Split in 1136, "enjoyed great favor with the kings of Hungary" and "often visited their court". The report suggests that Split accepted Béla II's suzerainty around 1136, but this interpretation of the sources is not universally accepted by historians. The exact circumstances surrounding the submission of Bosnia are unknown but the region seems to have accepted Béla's suzerainty without resistance by 1137. Historian John V. A. Fine writes that the northeastern regions of the province formed part of Queen Helena's dowry. The Hungarian army penetrated into the valley of the Rama River, a tributary of the Neretva River, in about 1137. Although Béla assumed the title King of Rama in token of the new conquest, the permanent occupation of the region is not proven.

Hungarian troops participated in a campaign launched by Grand Prince Yaropolk II of Kiev against Vsevolod of Kiev in 1139. Béla strengthened his alliance with the Holy Roman Empire. For this purpose, he gave financial support to Otto of Bamberg's missions among the Pomeranians and arranged the engagement of his daughter Sophia with Henry, son of the new German king Conrad III in June 1139.

Géza II was the oldest son of Béla the Blind and his wife, Helena of Serbia. When his father died, Géza was still a child and he started ruling under the guardianship of his mother and her brother, Beloš. A pretender to the throne, Boris Kalamanos, who had already claimed Hungary during Béla the Blind's reign, temporarily captured Pressburg (now Bratislava in Slovakia) with the assistance of German mercenaries in early 1146. In retaliation, Géza, who came of age in the same year, invaded Austria and routed Henry Jasomirgott, Margrave of Austria, in the Battle of the Fischa.

Although the German–Hungarian relations remained tense, no major confrontations occurred when the German crusaders marched through Hungary in June 1147. Two months later, Louis VII of France and his crusaders arrived, along with Boris Kalamanos who attempted to take advantage of the crusade to return to Hungary. Géza joined the coalition that Louis VII and Roger II of Sicily formed against Conrad III of Germany and the Byzantine Emperor Manuel I Komnenos. The ancestors of the Transylvanian Saxons came to Hungary during Géza's reign. Western European knights and Muslim warriors from the Pontic steppes also settled in Hungary in this period. Géza even allowed his Muslim soldiers to take concubines.

Géza intervened at least six times in the fights for Kiev on behalf of Iziaslav II of Kiev either by sending reinforcements or by personally leading his troops to the Kievan Rus' between 1148 and 1155. He also waged wars against the Byzantine Empire on behalf of his allies, including his cousins, rulers of the Grand Principality of Serbia, but could not prevent the Byzantines from restoring their suzerainty over them. Conflicts emerged between Géza and his brothers, Stephen and Ladislaus, who fled from Hungary and settled in Emperor Manuel's court in Constantinople. Géza supported Frederick I, Holy Roman Emperor, against the Lombard League with auxiliary troops between 1158 and 1160.

German–Hungarian relations remained tenseas Boris attempted to take advantage of Conrad III's decision to lead a crusade to the Holy Land through Hungary. However Géza, who knew that "he could conquer more easily by gold than by force, poured out much money among the Germans and thus escaped an attack from them," according to the chronicler Odo of Deuil. The German crusaders marched across Hungary without major incident in June 1147.

The Illuminated Chronicle relates that some Hungarian noblemen promised Boris "if he could make his way into the kingdom, many would take him for their lord and, deserting the King, would cleave to him." Boris convinced two French noblemen to assist by hiding him among the French crusaders who followed the Germans towards the Holy Land. King Louis VII of France and his crusaders arrived in Hungary in August. Géza learnt that his opponent was with the French and demanded his extradition. Although Louis VII rejected this demand, he held Boris in custody and "took him out of Hungary," according to Odo of Deuil. Having left Hungary, Boris settled in the Byzantine Empire.

The battle was a victory for the Hungarian army, under the leadership of king Géza II, which defeated a Bavarian army led by duke Henry XI during an open battle.

Disputes among European powers led to the formation of two coalitions in the late 1140s. One alliance was formed by the Byzantine Emperor Manuel I Komnenos and Conrad III against Roger II of Sicily who had invaded Byzantine territories. Géza sided with Roger II and his allies, including the rebellious German prince, Welf VI and Uroš II of Serbia. Géza sent reinforcements to his brother-in-law, Grand Prince Iziaslav II, against Prince Vladimir of Chernigov in the spring of 1148. The Grand Principality of Serbia rebelled in 1149, forcing Emperor Manuel I to interrupt his preparations for an invasion of Southern Italy and invade Serbia in 1149. According to the emperor's panegyrist Theodore Prodromus, Hungarian forces supported the Serbs during the emperor's campaign. The Hypatian Codex says that Géza referred to his war against Emperor Manuel when excusing himself for refusing to send reinforcements to Iziaslav II whom Yuri Dolgorukiy, Prince of Suzdal, expelled from Kiev in August 1149. Hungarian auxiliaries supported Iziaslav II to reoccupy Kiev in the early spring of 1150, but before long Yuri Dolgorukiy expelled Iziaslav from the town. In autumn, Géza led his army against Volodimirko of Halych, who was Yuri Dolgorukiy's close ally. He captured Sanok, but Volodimirko bribed the Hungarian commanders, who persuaded Géza to leave Halych before November.

Géza sent reinforcements to Iziaslav II who again reoccupied Kiev before April 1151. Three months later, Volodimirko of Halych routed a Hungarian army that was marching towards Kiev. Frederick Barbarossa, the newly elected King of Germany, demanded the German princes' consent to wage war against Hungary at the Imperial Diet of June 1152, but the princes refused him "for certain obscure reasons", according to Otto of Freising.

Géza invaded Halych in the summer of 1152. The united armies of Géza and Iziaslav defeated Volodimirko's troops at the San River, forcing Volodimirko to sign a peace treaty with Iziaslav. Pope Eugenius III sent his envoys to Hungary to strengthen the "faith and discipline" of the Hungarian church. Géza forbade the papal envoys to enter Hungary, which shows that his relationship with the Holy See had deteriorated.

Stephen III was King of Hungary and Croatia between 1162 and 1172. He was crowned king in early June 1162, shortly after the death of his father, Géza II. However, his two uncles, Ladislaus and Stephen, who had joined the court of the Byzantine Empire, challenged his right to the crown. Only six weeks after his coronation, the Byzantine Emperor Manuel I Komnenos launched an expedition against Hungary, forcing the Hungarian lords to accept Ladislaus' rule. Stephen sought refuge in Austria, but returned and seized Pressburg (now Bratislava in Slovakia). Ladislaus, who died on 14 January 1163, was succeeded by Stephen's younger uncle and namesake, Stephen IV, without resistance, but his rule was unpopular. The young Stephen defeated his uncle on 19 June 1163 and expelled him from Hungary.

Stephen IV attempted to regain his throne with Emperor Manuel I's support, but the latter made peace with Stephen III. He agreed to send his younger brother, Béla, to Constantinople and to allow the Byzantines to seize Béla's duchy, which included Croatia, Dalmatia and Sirmium. In an attempt to recapture these territories, Stephen III waged wars against the Byzantine Empire between 1164 and 1167, but could not defeat the Byzantines.

Stephen III invaded Dalmatia, although he had pledged to Vitale II Michiel, Doge of Venice, that he would withdraw from the Dalmatian towns. Upon Stephen's arrival the citizens of Zadar expelled the Venetian governor and accepted his suzerainty. He again stormed into Sirmium and laid siege to his uncle in Zimony in spring 1165. Byzantine Emperor Manuel decided to make a counterattack, but a rebellion by his cousin Andronikos Komnenos prevented him from marching to the Danube. Nevertheless, Manuel I sent envoys to the monarchs who had earlier supported Stephen III, persuading them to remain neutral in the conflict. Stephen III's uncle died of poisoning during the siege of Zimony, on 11 April. The fortress soon fell to Stephen III.

The Byzantine counter-offensive started at the end of June. An army under the command of Emperor Manuel I laid siege to Zimony and recaptured it; another Byzantine force invaded and occupied Bosnia and Dalmatia. The Venetian fleet intervened on the Byzantines' side in Dalmatia, forcing Zadar to again accept the rule of the Doge. Stephen III could only conclude a new peace treaty with Emperor Manuel after he renounced Sirmium and Dalmatia.

A Hungarian army under the command of Ispán Denis stormed into Sirmium once more in spring 1166. The Hungarians routed a Byzantine army, and occupied the whole province with the exception of Zimony. Emperor Manuel sent three armies against Hungary. The first army, which was under the command of protostrator Alexios Axuch and Stephen III's brother, Béla, was stationed by the Danube to distract attention from the movements of the two other units, which plundered Transylvania under the command of Leon Batatzes and John Doukas. The Byzantine campaign caused great devastation in the eastern territories of the Kingdom of Hungary, forcing Stephen III to seek reconciliation.

Emperor Manuel dispatched an army to Sirmium and sent his fleet to Zimony after Easter 1167. The Hungarians assembled their troops, and recruited mercenaries, especially Germans, according to Choniates. However, the Byzantine army led by Andronikos Kontostephanos annihilated the Hungarians, who were under the command of Ispán Denis, in a decisive battle which was fought near Zimony on 8 July.

The Hungarians sued for peace on Byzantine terms and recognised the empire’s control over Bosnia, Dalmatia, Croatia south of the Krka River as well as the Fruška Gora. They also agreed to provide hostages for good behaviour; to pay Byzantium a tribute and supply troops when requested.

Béla fought with his younger brother, Géza, whom he held in captivity for more than a decade. Taking advantage of the internal conflicts in the Byzantine Empire after Emperor Manuel's death, Béla reoccupied Croatia, Dalmatia and Sirmium between 1180 and 1181. He occupied the Principality of Halych in 1188, but it was lost within two years.

Béla promoted the use of written records during his reign. This emergence evidences the employment of an educated staff. Indeed, students from the kingdom studied at the universities of Paris, Oxford, Bologna, and Padua from the 1150s. Aspects of 12th-century French culture could also be detected in Béla's kingdom. His palace at Esztergom was built in the early Gothic style. According to the consensual scholarly view, "Master P", the author of the Gesta Hungarorum, a chronicle on the Hungarian "land-taking", was Béla's notary. The earliest text written in Hungarian, known as Funeral Sermon and Prayer, was preserved in the late 12th-century Pray Codex. Hungarian chronicles from the 14th century even state that he was responsible for the establishment of the Royal Chancery.

Upon Béla's invitation, Cistercian monks came from France and set up new Cistercian abbeys at Egres, Zirc, Szentgotthárd and Pilis between 1179 and 1184.

Emperor Manuel I died on 24 September 1180. Within six months, Béla had restored his suzerainty in Dalmatia, but no detailed contemporaneous accounts of the events exist. The citizens of Split "returned to Hungarian lordship" soon after Manuel's death, according to the 13th-century Thomas the Archdeacon. Zadar also accepted Béla's suzerainty in early 1181. Historian John V. A. Fine writes that Béla retook suzerainty of Dalmatia "seemingly without bloodshed and with imperial consent", because the Byzantine authorities preferred that Béla rule the province rather than the Republic of Venice.

In the summer of 1189, German crusaders marched through Hungary under the command of Frederick I, Holy Roman Emperor. Béla welcomed Frederick, and dispatched a troop to escort the crusaders across the Balkan Peninsula. At Frederick's request, Béla released his imprisoned brother, Géza, who joined the crusaders and left Hungary. Béla mediated a peace treaty between Frederick I and Isaac II, whose mutual distrust had almost caused war between the German crusaders and the Byzantines.

Emeric was King of Hungary and Croatia between 1196 and 1204. In 1184, his father, Béla III of Hungary, ordered that he be crowned king, and appointed him as ruler of Croatia and Dalmatia around 1195. Emeric ascended the throne after the death of his father. During the first four years of his reign, he fought his rebellious brother, Andrew, who forced Emeric to make him ruler of Croatia and Dalmatia as appanage.

Emeric cooperated with the Holy See against the Bosnian Church, which the Catholic Church considered to be heretics. Taking advantage of a civil war, Emeric expanded his suzerainty over Serbia. He failed to prevent the Republic of Venice, which was assisted by crusaders of the Fourth Crusade, from seizing Zadar in 1202. He also could not impede the rise of Bulgaria along the southern frontiers of his kingdom. Emeric was the first Hungarian monarch to use the "Árpád stripes" as his personal coat of arms and to adopt the title of King of Serbia.

In the summer of 1202, the Venetian doge Enrico Dandolo signed a treaty with the leaders of the Fourth Crusade, who agreed to help the Venetians recapture Zadar, a town in Dalmatia, which had accepted the Hungarian monarchs' suzerainty since 1186. Even though Pope Innocent III forbade the crusaders to besiege Zadar, they seized the town on 24 November and gave it to the Venetians. Although the Pope excommunicated the Venetians and the crusaders upon Emeric's demand, Zadar remained under Venetian rule.

During his reign, Andrew was intensely interested in the internal affairs of his former principality of Halych. He launched his first campaign to recapture Halych in 1205 or 1206. Andrew adopted the title of "King of Galicia and Lodomeria", demonstrating his claim to suzerainty in the two Rus' principalities. After Andrew returned to Hungary, Vsevolod Svyatoslavich's distant cousin, Vladimir Igorevich, seized both Halych and Lodomeria. 

Taking advantage of a conflict between Roman Igorevich and his boyars, Andrew sent troops to Halych under the command of Benedict, son of Korlát. Benedict captured Roman Igorevich and occupied the principality in 1208 or 1209. Roman Igorevich reconciled with his brother, Vladimir Igorevich, in early 1209 or 1210. Their united forces vanquished Benedict's army, expelling the Hungarians from Halych.

Andrew's rule was unpopular, and the boyars (or noblemen) expelled him. Béla III willed property and money to Andrew, obliging him to lead a crusade to the Holy Land. Instead, Andrew forced his elder brother, King Emeric of Hungary, to cede Croatia and Dalmatia as an appanage to him in 1197. The following year, Andrew occupied Hum. Despite the fact that Andrew did not stop conspiring against Emeric, the dying king made Andrew guardian of his son, Ladislaus III, in 1204. After the premature death of Ladislaus, Andrew ascended the throne in 1205.

He waged at least a dozen wars to seize the two Rus' principalities, but was repelled by the local boyars and neighboring princes. He participated in the Fifth Crusade to the Holy Land in 1217–1218, but the crusade was a failure.

When the servientes regis, or "royal servants", rose up, Andrew was forced to issue the Golden Bull of 1222, confirming their privileges. This led to the rise of the nobility in the Kingdom of Hungary. The employment of Jews and Muslims to administer the royal revenues led him into conflict with the Holy See and the Hungarian prelates. Andrew pledged to respect the privileges of the clergymen and to dismiss his non-Christian officials in 1233, but he never fulfilled the latter promise.

In the early 1210s, Andrew sent "an army of Saxons, Vlachs, Székelys and Pechenegs" commanded by Joachim, Count of Hermannstadt, (now Sibiu, Romania) to assist Boril of Bulgaria's fight against three rebellious Cuman chieftains.

Andrew's army defeated the Cumans at Vidin. Andrew granted the Barcaság (now Țara Bârsei, Romania) to the Teutonic Knights. The Knights were to defend the easternmost regions of the Kingdom of Hungary against the Cumans and encourage their conversion to Catholicism.

Andrew invades Halych in the summer of 1213. Then he jointly invaded it with Leszek of Poland in 1214 and Andrew's second son, Coloman was made price. Leszek of Poland soon reconciled with Mstislav Mstislavich; they jointly invaded Halych and forced Coloman to flee to Hungary. Andrew signed a new treaty of alliance with Leszek of Poland in the summer of 1216. Leszek and Andrew's son, Coloman, invaded Halych and expelled Mstislav Mstislavich and Daniel Romanovich, after which Coloman was restored. 

In July 1216, the newly elected Pope Honorius III once again called upon Andrew to fulfill his father's vow to lead a crusade. Andrew, who had postponed the crusade at least three times (in 1201, 1209 and 1213), finally agreed. Steven Runciman, Tibor Almási and other modern historians say that Andrew hoped that his decision would increase his likelihood of being elected as Latin Emperor of Constantinople, because his wife's uncle, Emperor Henry, had died in June. According to a letter written by Pope Honorius in 1217, envoys from the Latin Empire had actually informed Andrew that they planned to elect either him or his father-in-law, Peter of Courtenay, as emperor. Nonetheless, the barons of the Latin Empire elected Peter of Courtenay in the summer of 1216.

Andrew sold and mortgaged royal estates to finance his campaign, which became part of the Fifth Crusade. He renounced his claim to Zadar in favor of the Republic of Venice so that he could secure shipping for his army. He entrusted Hungary to Archbishop John of Esztergom, and entrusted Croatia and Dalmatia to Pontius de Cruce, the Templar prior of Vrana. In July 1217, Andrew departed from Zagreb, accompanied by Dukes Leopold VI of Austria and Otto I of Merania. His army was so large—at least 10,000 mounted soldiers and uncountable infantrymen—that most of it stayed behind when Andrew and his men embarked in Split two months later. The ships transported them to Acre, where they landed in October.

The leaders of the crusade included John of Brienne, King of Jerusalem, Leopold of Austria, the Grand Masters of the Hospitallers, the Templars and the Teutonic Knights. They held a war council in Acre, with Andrew leading the meeting. In early November, the Crusaders launched a campaign for the Jordan River, forcing Al-Adil I, Sultan of Egypt, to withdraw without fighting; the crusaders then pillaged Beisan. After the crusaders returned to Acre, Andrew did not participate in any other military actions. Instead, he collected relics, including a water jug allegedly used at the marriage at Cana, the heads of Saint Stephen and Margaret the Virgin, the right hands of the Apostles Thomas and Bartholomew and a part of Aaron's rod. If Thomas the Archdeacon's report of certain "evil and audacious men" in Acre who "treacherously passed him a poisoned drink" is reliable, Andrew's inactivity was because of illness.

Andrew decided to return home at the very beginning of 1218, even though Raoul of Merencourt, Latin Patriarch of Jerusalem, threatened him with excommunication. When he arrived in Bulgaria, Andrew was detained until he "gave full surety that his daughter would be united in marriage" to Ivan Asen II of Bulgaria, according to Thomas the Archdeacon. Andrew returned to Hungary in late 1218. Andrew's "crusade had achieved nothing and brought him no honor", according to historian Thomas Van Cleve.

The Golden Bull of 1222 was a golden bull, or edict, issued by Andrew II of Hungary. King Andrew II was forced by his nobles to accept the Golden Bull (Aranybulla), which was one of the first examples of constitutional limits being placed on the powers of a European monarch.

The Golden Bull was issued at the year 1222 diet of Fehérvár. The law established the rights of the Hungarian nobility, including the right to disobey the King when he acted contrary to law (jus resistendi). The nobles and the church were freed from all taxes and could not be forced to go to war outside of Hungary and were not obligated to finance it. This was also a historically important document because it set down the principles of equality for all of the nation's nobility.

The charter's creation was influenced by the emergence of a nobility middle class, unusual in the nation's feudal system. As a regular gesture of generosity, King Andrew often donated property to particularly faithful servants, who thereafter gained new economic and class power. With the nation's class system and economic state changing, King Andrew found himself coerced into decreeing the Golden Bull of 1222 to relax tensions between hereditary nobles and the budding middle class nobility.The Golden Bull is often compared to Magna Carta; the Bull was the first constitutional document of the nation of Hungary, while Magna Carta was the first constitutional charter of the nation of England.

Andrew launched a campaign against the Teutonic Knights, who had attempted to eliminate his suzerainty. The Knights were forced to leave Barcaság and the neighboring lands. Andrew's envoys and Leopold VI of Austria signed a treaty on 6 June, which ended the armed conflicts along the Hungarian-Austrian border. As part of the treaty, Leopold VI paid an indemnification for the damages that his troops had caused in Hungary.

Andrew employed Jews and Muslims to administer royal revenues, which caused a discord between Andrew and the Holy See starting in the early 1220s. Pope Honorius urged Andrew and Queen Yolanda to prohibit Muslims from employing Christians. Archbishop Robert excommunicated Palatine Denis and put Hungary under an interdict on 25 February 1232, because the employment of Jews and Muslims continued despite the Golden Bull of 1231. Since the archbishop accused the Muslims of persuading Andrew to seize church property, Andrew restored properties to the archbishop, who soon suspended the interdict. 

On 20 August 1233, in the forests of Bereg, he vowed that he would not employ Jews and Muslims to administrate royal revenues, and would pay 10,000 marks as compensation for usurped Church revenues.

John, Bishop of Bosnia, put Hungary under a new interdict in the first half of 1234, because Andrew had not dismissed his non-Christian officials despite his oath of Bereg.

Béla IV supported Christian missions among the pagan Cumans who dwelled in the plains to the east of his province. Some Cuman chieftains acknowledged his suzerainty and he adopted the title of King of Cumania in 1233. He attempted to restore royal authority, which had diminished under his father. For this purpose, he revised his predecessors' land grants and reclaimed former royal estates, causing discontent among the noblemen and the prelates.

The Mongols invaded Hungary and annihilated Béla's army in the Battle of Mohi on 11 April 1241. He escaped from the battlefield, but a Mongol detachment chased him from town to town as far as Trogir on the coast of the Adriatic Sea. Although he survived the invasion, the Mongols devastated the country before their unexpected withdrawal in March 1242. Béla introduced radical reforms in order to prepare his kingdom for a second Mongol invasion. He allowed the barons and the prelates to erect stone fortresses and to set up their private armed forces. He promoted the development of fortified towns. During his reign, thousands of colonists arrived from the Holy Roman Empire, Poland and other neighboring regions to settle in the depopulated lands. Béla's efforts to rebuild his devastated country won him the epithet of "second founder of the state". He set up a defensive alliance against the Mongols. During Béla's reign, a wide buffer zone—which included Bosnia, Barancs and other newly conquered regions—was established along the southern frontier of Hungary in the 1250s.

Béla's relationship with his oldest son and heir, Stephen, became tense in the early 1260s, because the elderly king favored his daughter Anna and his youngest child, Béla, Duke of Slavonia. He was forced to cede the territories of the Kingdom of Hungary east of the river Danube to Stephen, which caused a civil war lasting until 1266. 

After returning from Magna Hungaria in 1236, Friar Julian informed Béla of the Mongols, who had by that time reached the Volga River and were planning to invade Europe. The Mongols invaded Desht-i Qipchaq—the westernmost regions of the Eurasian Steppes—and routed the Cumans. Fleeing the Mongols, at least 40,000 Cumans approached the eastern borders of the Kingdom of Hungary and demanded admission in 1239. Béla only agreed to give them shelter after their leader, Köten, promised to convert together with his people to Christianity, and to fight against the Mongols. However, the settlement of masses of nomadic Cumans in the plains along the Tisza River gave rise to many conflicts between them and the local villagers. Béla, who needed the Cumans' military support, rarely punished them for their robberies, rapes and other misdeeds. His Hungarian subjects thought that he was biased in the Cumans' favor, thus "enmity emerged between the people and the king", according to Roger of Torre Maggiore.

The Hungarians had first learned about the Mongol threat in 1229, when King Andrew II granted asylum to some fleeing Russian boyars. Some Magyars (Hungarians), left behind during the main migration to the Pannonian basin, still lived on the banks of the upper Volga (it is believed by some that the descendants of this group are the modern-day Bashkirs, although this people now speaks a Turkic language, not Magyar).

In 1237 a Dominican friar, Julianus, set off on an expedition to lead them back, and was sent back to King Béla with a letter from Batu Khan. In this letter, Batu called upon the Hungarian king to surrender his kingdom unconditionally to the Tatar forces or face complete destruction. Béla did not reply, and two more messages were later delivered to Hungary. The first, in 1239, was sent by the defeated Cuman tribes, who asked for and received asylum in Hungary. The second was sent in February 1241 from Poland which was facing an invasion from another Mongol force.

Five separate Mongol armies invaded Hungary in 1241. The main army under Batu and Subutai crossed through the Verecke Pass. The army of Qadan and Büri crossed through the Tihuța Pass. Two smaller forces under Böchek and the noyan Bogutai entered Hungary from the southeast. The army that had invaded Poland under Orda and Baidar invaded Hungary from the northwest.

During the summer and autumn of 1241, most of the Mongol forces were resting on the Hungarian Plain. In late March, 1242, they began to withdraw. The most common reason given for this withdrawal is the Great Khan Ögedei's death on December 11, 1241, which supposedly forced the Mongols to retreat to Mongolia so that the princes of the blood could be present for the election of a new great khan. 

The true reasons for the Mongol withdrawal are not fully known, but numerous plausible explanations exist. Regardless of their reasons, the Mongols had completely withdrawn from Central Europe by mid-1242, though they still launched military operations in the west at this time, most notably the 1241–1243 Mongol invasion of Anatolia.

The effects of the Mongol invasion were tremendous in the Kingdom of Hungary. The worst damage was incurred in the plains regions, where 50-80% of settlements were destroyed. The combination of massacres perpetrated by the Mongols, the famines induced by their foraging, and the simultaneous devastation of the countryside by the fleeing Cumans resulted in an estimated loss of 15–25% of Hungary's population, some 300,000–500,000 people in total. The only places that held in the face of Mongol assaults were approximately eighty fortified places, including all of the few stone castles in the kingdom. Among these places were Esztergom, Székesfehérvár, and the Pannonhalma Archabbey. However, these places were relatively few; a German chronicler in 1241 noted that Hungary "had almost no city protected by strong walls or fortresses", so the majority of settled areas were extremely vulnerable.

Upon his return to Hungary in May 1242, Béla found a country in ruins. Devastation was especially heavy in the plains east of the Danube where at least half of the villages were depopulated. The Mongols had destroyed most traditional centers of administration, which were defended by earth-and-timber walls. A severe famine followed in 1242 and 1243.

Preparation for a new Mongol invasion was the central concern of Béla's policy. In a letter of 1247 to Pope Innocent IV, Béla announced his plan to strengthen the Danube—the "river of confrontations"—with new forts. He abandoned the ancient royal prerogative to build and own castles, promoting the erection of nearly 100 new fortresses by the end of his reign. 

Béla attempted to increase the number of the soldiers and to improve their equipment. He made land grants in the forested regions and obliged the new landowners to equip heavily armoured cavalrymen to serve in the royal army. He even allowed the barons and prelates to employ armed noblemen, who had previously been directly subordinated to the sovereign, in their private retinue (banderium). 

To replace the loss of at least 15 percent of the population, Béla promoted colonization. He granted special liberties to the colonists, including personal freedom and favorable tax treatment. Germans, Moravians, Poles, Ruthenians and other "guests" arrived from neighboring countries and were settled in depopulated or sparsely populated regions. He also persuaded the Cumans, who had in 1241 left Hungary, to return and settle in the plains along the River Tisza. He even arranged the engagement of his firstborn son, Stephen, who was crowned king-junior in or before 1246, to Elisabeth, a daughter of a Cuman chieftain.

Béla adopted an active foreign policy soon after the withdrawal of the Mongols. In the second half of 1242 he invaded Austria and forced Duke Frederick II to surrender the three counties ceded to him during the Mongol invasion. On the other hand, Venice occupied Zadar in the summer of 1243. Béla renounced Zadar on 30 June 1244, but Venice acknowledged his claim to one third of the customs revenues of the Dalmatian town.

On 21 August 1245 Pope Innocent IV freed Béla of the oath of fidelity he had taken to Emperor Frederick during the Mongol invasion. In the following year Duke Frederick II of Austria invaded Hungary. He routed Béla's army in the Battle of the Leitha River on 15 June 1246, but perished in the battlefield. His childless death gave rise to a series of conflicts, because both his niece, Gertrude, and his sister, Margaret, made a claim to Austria and Styria. Béla decided to intervene in the conflict only after the danger of a second Mongol invasion had diminished by the end of the 1240s. In retaliation of a former Austrian incursion into Hungary, Béla made a plundering raid into Austria and Styria in the summer of 1250. In this year he met and concluded a peace treaty with Daniil Romanovich, Prince of Halych in Zólyom (Zvolen, Slovakia). With Béla's mediation, a son of his new ally Roman married Gertrude of Austria.

Béla and Daniil Romanovich united their troops and invaded Austria and Moravia in June 1252. After their withdrawal, Ottokar, Margrave of Moravia—who had married Margaret of Austria—invaded and occupied Austria and Styria. In the summer of 1253, Béla launched a campaign against Moravia and laid siege to Olomouc. Daniil Romanovich, Boleslaw the Chaste of Cracow, and Wladislaw of Opole intervened on Béla's behalf, but he lifted the siege by the end of June. Pope Innocent IV mediated a peace treaty, which was signed in Pressburg (Bratislava, Slovakia) on 1 May 1254. In accordance with the treaty, Ottokar, who had in the meantime become King of Bohemia, ceded Styria to Béla.

Discontented with the rule of Béla's son, the Styrian lords sought assistance from Ottokar of Bohemia. Béla and his allies—Daniil Romanovich, Boleslaw the Chaste, and Leszek the Black of Sieradz—invaded Moravia, but Ottokar vanquished them in the Battle of Kressenbrunn on 12 June 1260. 

The fight is considered one of the biggest battles in Central Europe in the Middle Ages, though scholars doubt the possibility of supplying such a vast number of mercenaries. After Ottokar's victory, King Béla renounced the Duchy of Styria and in 1261 even arranged the marriage of his granddaughter Kunigunda of Slavonia with the Bohemian king. However his successors continued to challenge the Bohemian kingdom.

The Battle of Isaszeg was fought between King Béla IV of Hungary and his son, Stephen, who served as Junior King and Duke of Transylvania. Stephen defeated his father's army in the subsequent peace Béla was obliged to cede the government of the Eastern parts of his kingdom again to his son.

Béla's favoritism towards his younger son, Béla (whom he appointed Duke of Slavonia) and daughter, Anna irritated Stephen. The latter suspected that his father was planning to disinherit him. The relationship between father and son remained tense. Stephen seized his mother's and sister's estates which were situated in his realm to the east of the Danube. Béla's army under Anna's command crossed the Danube in the summer of 1264. She occupied Sárospatak and captured Stephen's wife and children. A detachment of the royal army, under the command of Béla's Judge royal Lawrence forced Stephen to retreat as far as the fortress at Feketehalom (Codlea, Romania) in the easternmost corner of Transylvania. The king-junior's partisans relieved the castle and he started a counter-attack in the autumn. In the decisive Battle of Isaszeg, he routed his father's army in March 1265.

It was again the two archbishops who conducted the negotiations between Béla and his son. Their agreement was signed in the Dominican Monastery of the Blessed Virgin on Rabbits' Island (Margaret Island, Budapest) on 23 March 1266. The new treaty confirmed the division of the country along the Danube and regulated many aspects of the co-existence of Béla's regnum and Stephen's regimen, including the collection of taxes and the commoners' right to free movement.

During Ladislaus IV's minority, many groupings of barons — primarily the Abas, Csáks, Kőszegis, and Gutkeleds — fought against each other for supreme power. Ladislaus was declared to be of age at an assembly of the prelates, barons, noblemen, and Cumans in 1277. He allied himself with Rudolf I of Germany against Ottokar II of Bohemia. His forces had a preeminent role in Rudolf's victory over Ottokar in the Battle on the Marchfeld on 26 August 1278.

However, Ladislaus could not restore royal power in Hungary. A papal legate, Philip, bishop of Fermo, came to Hungary to help Ladislaus consolidate his authority, but the prelate was shocked at the presence of thousands of pagan Cumans in Hungary. Ladislaus promised that he would force them to adopt a Christian lifestyle, but they refused to obey the legate's demands. Ladislaus decided to support the Cumans, for which Philip of Fermo excommunicated him. The Cumans imprisoned the legate, and the legate's partisans captured Ladislaus. In early 1280, Ladislaus agreed to persuade the Cumans to submit to the legate, but many Cumans preferred to leave Hungary.

Ladislaus vanquished a Cuman army that invaded Hungary in 1282. Hungary also survived a Mongol invasion in 1285. Ladislaus had, by that time, become so unpopular that many of his subjects accused him of inciting the Mongols to invade Hungary. After he imprisoned his wife in 1286, he lived with his Cuman mistresses. During the last years of his life, he wandered throughout the country with his Cuman allies, but he was unable to control the most powerful lords and bishops any more. Pope Nicholas IV planned to declare a crusade against him, but three Cuman assassins murdered Ladislaus.

Pope Nicholas III sent Philip, bishop of Fermo, to Hungary to help Ladislaus restore royal power on 22 September 1278. The papal legate arrived in Hungary in early 1279. With the legate's mediation, Ladislaus concluded a peace treaty with the Kőszegis. Bishop Philip soon realized, however, that most Cumans were still pagans in Hungary. He extracted a ceremonious promise from the Cuman chieftains of giving up their pagan customs, and persuaded the young King Ladislaus to swear an oath to enforce the keeping of the Cuman chieftains' promise. The Cumans did not obey the laws, however, and Ladislaus, himself a half-Cuman, failed to force them. In retaliation, Bishop Philip excommunicated him and placed Hungary under interdict in October. Ladislaus joined the Cumans and appealed to the Holy See, but the Pope refused to absolve him.

On Ladislaus's demand, the Cumans seized and imprisoned Philip of Fermo in early January 1280. However, Finta Aba, voivode of Transylvania captured Ladislaus and handed him over to Roland Borsa. In less than two months, both the legate and the king were set free and Ladislaus took a new oath to enforce the Cuman laws. However, many Cumans decided to leave Hungary instead of obeying the legate's demands. Ladislaus followed the moving Cumans as far as Szalánkemén (now Stari Slankamen in Serbia), but could not hinder them from crossing the frontier.

 A Cuman army invaded the southern parts of Hungary in 1282. The Illuminated Chronicle writes that Ladislaus, "like the brave Joshua, went out against" the Cumans "to fight for his people and his realm." He vanquished the invaders's army at Lake Hód, near Hódmezővásárhely, in the autumn of 1282.. King Ladislaus IV of Hungary successfully repelled the invaders.

The 1282 Cuman rebellion may have catalyzed the Mongol invasion. Cuman warriors driven out of Hungary offered their services to Nogai Khan, de facto head of the Golden Horde, and told him about the perilous political situation in Hungary. Seeing this as an opportunity, Nogai decided to start a vast campaign against the apparently weak kingdom.

In the winter of 1285, Mongol armies invaded Hungary for a second time. As in the first invasion in 1241, Mongols invaded Hungary in two fronts. Nogai invaded via Transylvania, while Talabuga invaded via Transcarpathia and Moravia. A third, smaller force likely entered the center of the kingdom, mirroring Kadan's earlier route. The invasion paths seemed to mirror those taken by Batu and Subutai 40 years earlier, with Talabuga going through Verecke Pass and Nogai going through Brassó to enter Transylvania. Much like the first invasion, the Mongols emphasized speed and surprise and intended to destroy the Hungarian forces in detail, invading in winter for hope of catching the Hungarians off guard and moving fast enough that it was impossible (at least until their later setbacks) for Ladislaus to gather enough men to engage them in a decisive confrontation. Because of the lack of civil war in the Mongol Empire at the time, as well as the lack of any other major conflicts involving the Golden Horde, Nogai was able to field a very large army for this invasion, with the Galician-Volhynian Chronicle describing it as "a great host" but its exact size isn't certain. It is known that the Mongol host included cavalry from their vassals, the Ruthenian princes, including Lev Daniilovich and others from among their Rus′ satellites.

The results of the invasion could not have contrasted more sharply with those of the 1241 invasion. The invasion was repelled handily, and the Mongols lost much of their invading force due to several months of starvation, numerous small raids, and two major military defeats. This was mostly thanks to the new fortification network and the military reforms. No major invasion of Hungary would be launched after the failure of the campaign of 1285, though small raids from the Golden Horde were frequent well into the 14th century. 

While a victory for Hungary overall (albeit with heavy civilian casualties), the war was a political disaster for the king. Like his grandfather before him, many nobles accused him of inviting the Mongols into his lands, due to his perceived ties to the Cumans.

Ladislaus spent the last years of his life wandering from place to place. Hungary's central government lost power because the prelates and the barons ruled the kingdom independently of the monarch. For example, Ivan Kőszegi and his brothers waged wars against Albert I, Duke of Austria, but Ladislaus did not intervene, although the Austrians captured at least 30 fortresses along the western borders.

Ladislaus, who had always been partial towards his Cuman subjects, was assassinated by three Cumans, named Árbóc, Törtel, and Kemence, at the castle of Körösszeg (now Cheresig in Romania) on 10 July 1290. Mizse and the Cuman Nicholas, who was the brother of Ladislaus's Cuman lover, took vengeance for Ladislaus's death, slaughtering the murderers. Archbishop Lodomer subsequently dispatched two monks to Vienna to inform Andrew of the king's death. With the monks' assistance, Andrew left his prison in disguise and hastened to Hungary.

Being the last male member of the House of Árpád, Andrew was elected king after the death of King Ladislaus IV in 1290. He was the first Hungarian monarch to issue a coronation diploma confirming the privileges of the noblemen and the clergy. At least three pretenders—Albert of Austria, Mary of Hungary, and an adventurer—challenged his claim to the throne. Andrew expelled the adventurer from Hungary and forced Albert of Austria to conclude a peace within a year, but Mary of Hungary and her descendants did not renounce their claim. The Hungarian bishops and Andrew's maternal family from Venice were his principal supporters, but the leading Croatian and Slavonian lords were opposed to his rule.

Hungary was in a state of constant anarchy during Andrew's reign. The Kőszegis, the Csáks, and other powerful families autonomously governed their domains, rising up nearly every year in open rebellion against Andrew. With Andrew's death, the House of Árpád became extinct. A civil war ensued which lasted for more than two decades and ended with the victory of Mary of Hungary's grandson, Charles Robert.

A group of powerful lords—including the Šubići, Kőszegis and Csáks—urged Charles II of Naples to send his grandson, the 12-year-old Charles Robert, to Hungary in order to become king. The young Charles Robert disembarked in Split in August 1300. Most Croatian and Slavonian lords and all Dalmatian towns but Trogir recognized him as king before he marched to Zagreb. The Kőszegis and Matthew Csák, however, were shortly reconciled with Andrew, preventing Charles' success. Andrew's envoy to the Holy See noted that Pope Boniface VIII did not support Charles Robert's adventure, either. Andrew, who had been in poor health for a while, was planning to capture his opponent, but he died in Buda Castle on 14 January 1301. According to historians Attila Zsoldos and Gyula Kristó, the contemporaneous gossip suggesting that Andrew was poisoned cannot be proved.

Years later, Palatine Stephen Ákos referred to Andrew as the "last golden branch" of the tree of King Saint Stephen's family, because with Andrew's death the House of Árpád, the first royal dynasty of Hungary, ended. A civil war between various claimants to the throne—Charles Robert, Wenceslaus of Bohemia, and Otto of Bavaria—followed Andrew's death and lasted for seven years. The civil war ended with Charles Robert's victory, but he was forced to continue fighting against the Kőszegis, the Abas, Matthew Csák, and other powerful lords up to the early 1320s.