The Kingdom of Hungary came into being when Stephen I, grand prince of the Hungarians, was crowned king in 1000 or 1001. He reinforced central authority and forced his subjects to accept Christianity. Civil wars, pagan uprisings and the Holy Roman Emperors' unsuccessful attempts to expand their authority over Hungary jeopardized the new monarchy. Its position stabilized under Ladislaus I (1077–1095) and Coloman (1095–1116). Following the succession crisis in Croatia as a result of their campaign the Kingdom of Croatia entered a personal union with the Kingdom of Hungary in 1102.

Rich in uncultivated lands and in silver, gold, and salt deposits, the kingdom became a preferred target of the continuous immigration of mainly German, Italian and French colonists. Situated at the crossroads of international trade routes, Hungary was affected by several cultural trends. Romanesque, Gothic and Renaissance buildings, and literary works written in Latin prove the predominantly Roman Catholic character of the culture of the Kingdom, but Orthodox, and even non-Christian ethnic minority communities also existed. Latin was the language of legislation, administration and judiciary, but "linguistic pluralism" contributed to the survival of a number of tongues, including a great variety of Slavic dialects.

The predominance of royal estates initially ensured the sovereign's preeminent position, but the alienation of royal lands gave rise to the emergence of a self-conscious group of lesser landholders. They forced Andrew II to issue his Golden Bull of 1222, "one of first examples of constitutional limits being placed on the powers of a European monarch". The kingdom received a major blow from the Mongol invasion of 1241–1242. Thereafter Cuman and Jassic groups were settled in the central lowlands and colonists arrived from Moravia, Poland and other nearby countries.

Andrew III died on January 14, 1301. His death created an opportunity for about a dozen lords, or "oligarchs", who had by that time achieved de facto independence of the monarch to strengthen their autonomy. They acquired all royal castles in a number of counties where everybody was obliged either to accept their supremacy or to leave.

At the news of Andrew III's death, viceroy Šubić invited Charles of Anjou, the late Charles Martel's son, to claim the throne, who hurried to Esztergom where he was crowned king. However, most secular lords opposed his rule and proposed the throne to King Wenceslaus II of Bohemia's namesake son. The young Wenceslaus could not strengthen his position and renounced in favor of Otto III, Duke of Bavaria in 1305. The latter was forced to leave the kingdom in 1307 by Ladislaus Kán. A papal legate persuaded all the lords to accept Charles of Anjou's rule in 1310, but most territories remained out of royal control.

Assisted by the prelates and a growing number of lesser nobles, Charles I launched a series of expeditions against the great lords. Taking advantage of the lack of unity among them, he defeated them one by one. He won his first victory in the battle of Rozgony (present-day Rozhanovce, Slovakia) in 1312. However, the most powerful lord, Matthew Csák preserved his autonomy up until his death in 1321, while the Babonić and Šubić families were only subjugated in 1323.

Charles came to the Kingdom of Hungary upon the invitation of an influential Croatian lord, Paul Šubić, in August 1300. Andrew III died (the last of Árpád dynasty) on 14 January 1301 , and within four months Charles was crowned king, but with a provisional crown instead of the Holy Crown of Hungary. Most Hungarian noblemen refused to yield to him and elected Wenceslaus of Bohemia king. Charles withdrew to the southern regions of the kingdom. Pope Boniface VIII acknowledged Charles as the lawful king in 1303, but Charles was unable to strengthen his position against his opponent. 

Charles won his first decisive victory in the Battle of Rozgony (at present-day Rozhanovce in Slovakia) on 15 June 1312. During the next decade, Charles restored royal power primarily with the assistance of the prelates and lesser noblemen in most regions of the kingdom. After the death of the most powerful oligarch, Matthew Csák, in 1321, Charles became the undisputed ruler of the whole kingdom, with the exception of Croatia where local noblemen were able to preserve their autonomous status. He was not able to hinder the development of Wallachia into an independent principality after his defeat in the Battle of Posada in 1330.

Charles rarely made perpetual land grants, instead introduced a system of "office fiefs", whereby his officials enjoyed significant revenues, but only for the time they held a royal office, which ensured their loyalty. In the second half of his reign, Charles did not hold Diets and administered his kingdom with absolute power. He established the Order of Saint George, which was the first secular order of knights. He promoted the opening of new gold mines, which made Hungary the largest producer of gold in Europe. The first Hungarian gold coins were minted during his reign. At the congress of Visegrád in 1335, he mediated a reconciliation between two neighboring monarchs, John of Bohemia and Casimir III of Poland. Treaties signed at the same congress also contributed to the development of new commercial routes linking Hungary with Western Europe. Charles's efforts to reunite Hungary, together with his administrative and economic reforms, established the basis for the achievements of his successor, Louis the Great.

In 1312, Charles besieged Sáros Castle, (now part of Slovakia - Šariš Castle) controlled by the Abas. After the Abas received additional reinforcement from Máté Csák (according to Chronicon Pictum almost Máté's entire force as well as 1,700 mercenary spearmen), Charles Robert of Anjou was forced to retreat to the loyal Szepes county (today the region of Spiš), whose Saxon inhabitants subsequently reinforced his own troops. The Abas benefited from the retreat. They decided to use the gathered opposition forces to attack the town of Kassa (today Košice) because of its strategic importance. Charles marched on Kassa and engaged his adversaries. The Battle resulted in a decisive victory for Charles.

The immediate consequence was that Charles Robert of Hungary gained control over the northeastern part of the country. But the long-term consequences of the victory were even more important. The battle drastically reduced magnates' opposition against him. The King extended his power base and prestige. The position of Charles Robert as King of Hungary was now secured militarily and resistance against his rule came to its end.

Charles I promoted the opening of new gold mines, which made Hungary the largest producer of gold in Europe. The first Hungarian gold coins were minted during his reign. In the next few years, new gold mines were opened at Körmöcbánya (now Kremnica in Slovakia), Nagybánya (present-day Baia Mare in Romania) and Aranyosbánya (now Baia de Arieș in Romania). Hungarian mines yielded about 1,400 kilograms (3,100 lb) of gold around 1330, which made up more than 30% of the world's total production. The minting of gold coins began under Charles's auspices in the lands north of the Alps in Europe. His florins, which were modelled on the gold coins of Florence, were first issued in 1326. 

As one of his charters concluded, Charles had taken "full possession" of his kingdom by 1323. In the first half of the year, he moved his capital from Temesvár to Visegrád in the centre of his kingdom. In the same year, the Dukes of Austria renounced Pressburg (now Bratislava in Slovakia), which they had controlled for decades, in exchange for the support they had received from Charles against Louis IV, Holy Roman Emperor, in 1322.

Royal power was only nominally restored in the lands between the Carpathian Mountains and the Lower Danube, which had been united under a voivode, known as Basarab, by the early 1320s. Although Basarab was willing to accept Charles's suzerainty in a peace treaty signed in 1324, he refrained from renouncing control of the lands he had occupied in the Banate of Severin. Charles also attempted to reinstate royal authority in Croatia and Slavonia. He dismissed the Ban of Slavonia, John Babonić, replacing him with Mikcs Ákos in 1325. Ban Mikcs invaded Croatia to subjugate the local lords who had seized the former castles of Mladen Subić without the king's approval, but one of the Croatian lords, Ivan I Nelipac, routed the ban's troops in 1326. Consequently, royal power remained only nominal in Croatia during Charles's reign. The Babonići and the Kőszegis rose up in open rebellion in 1327, but Ban Mikcs and Alexander Köcski defeated them. In retaliation, at least eight fortresses of the rebellious lords were confiscated in Slavonia and Transdanubia.

In September 1330, Charles launched a military expedition against Basarab I of Wallachia who had attempted to get rid of his suzerainty. After seizing the fortress of Severin (present-day Drobeta-Turnu Severin in Romania), he refused to make peace with Basarab and marched towards Curtea de Argeș, which was Basarab's seat. The Wallachians applied scorched earth tactics, compelling Charles to make a truce with Basarab and withdraw his troops from Wallachia. 

While the royal troops were marching through a narrow pass across the Southern Carpathians on 9 November, the small Wallachian army, formed of cavalry and foot archers, as well as local peasants, managed to ambush and defeat the 30,000-strong Hungarian army. During the next four days, the royal army was decimated; Charles could only escape from the battlefield after changing his clothes with one of his knights, Desiderius Hédervári, who sacrificed his life to enable the king's escape. Charles did not attempt a new invasion of Wallachia, which subsequently developed into an independent principality.

In September 1331, Charles made an alliance with Otto the Merry, Duke of Austria, against Bohemia. He also sent reinforcements to Poland to fight against the Teutonic Knights and the Bohemians. In 1332 he signed a peace treaty with John of Bohemia and mediated a truce between Bohemia and Poland. In summer 1335, the delegates of John of Bohemia and the new King of Poland, Casimir III, entered into negotiations in Trencsén to put an end to the conflicts between the two countries. With Charles's mediation, a compromise was reached on 24 August: John of Bohemia renounced his claim to Poland and Casimir of Poland acknowledged John of Bohemia's suzerainty in Silesia. 

On 3 September, Charles signed an alliance with John of Bohemia in Visegrád, which was primarily formed against the Dukes of Austria. Upon Charles's invitation, John of Bohemia and Casimir of Poland met in Visegrád in November. During the Congress of Visegrád, the two rulers confirmed the compromise that their delegates had worked out in Trencsén. The three rulers agreed upon a mutual defence union against the Habsburgs, and a new commercial route was set up to enable merchants travelling between Hungary and the Holy Roman Empire to bypass Vienna.

The Babonići and the Kőszegis made an alliance with the Dukes of Austria in January 1336. John of Bohemia, who claimed Carinthia from the Habsburgs, invaded Austria in February. Casimir III of Poland came to Austria to assist him in late June. Charles soon joined them at Marchegg. The dukes sought reconciliation and signed a peace treaty with John of Bohemia in July. Charles signed a truce with them on 13 December, and launched a new expedition against Austria early the next year. He forced the Babonići and the Kőszegis to yield, and the latter were also compelled to hand over to him their fortresses along the frontier in exchange for faraway castles. Charles's peace treaty with Albert and Otto of Austria, which was signed on 11 September 1337, forbade both the dukes and Charles to give shelter to the other party's rebellious subjects.

Louis I inherited a centralized kingdom and a rich treasury from his father. During the first years of his reign, Louis launched a crusade against the Lithuanians and restored royal power in Croatia; his troops defeated a Tatar army, expanding his authority towards the Black Sea. When his brother, Andrew, Duke of Calabria, husband of Queen Joanna I of Naples, was assassinated in 1345, Louis accused the queen of his murder and punishing her became the principal goal of his foreign policy. He launched two campaigns to the Kingdom of Naples between 1347 and 1350. Louis's arbitrary acts and atrocities committed by his mercenaries made his rule unpopular in Southern Italy. He withdrew all his troops from the Kingdom of Naples in 1351.

Like his father, Louis administered Hungary with absolute power and used royal prerogatives to grant privileges to his courtiers. However, he also confirmed the liberties of the Hungarian nobility at the Diet of 1351, emphasizing the equal status of all noblemen. At the same Diet, he introduced an entail system and a uniform rent payable by the peasants to the landowners, and confirmed the right to free movement for all peasants. He waged wars against the Lithuanians, Serbia, and the Golden Horde in the 1350s, restoring the authority of Hungarian monarchs over territories along frontiers that had been lost during previous decades. He forced the Republic of Venice to renounce the Dalmatian towns in 1358. He also made several attempts to expand his suzerainty over the rulers of Bosnia, Moldavia, Wallachia, and parts of Bulgaria and Serbia. These rulers were sometimes willing to yield to him, either under duress or in the hope of support against their internal opponents, but Louis's rule in these regions was only nominal during most of his reign. His attempts to convert his pagan or Orthodox subjects to Catholicism made him unpopular in the Balkan states. Louis established a university in Pécs in 1367, but it was closed within two decades because he did not arrange for sufficient revenues to maintain it.

Louis inherited Poland after his uncle's death in 1370. In Hungary, he authorized the royal free cities to delegate jurors to the high court hearing their cases and set up a new high court. At the beginning of the Western Schism, he acknowledged Urban VI as the legitimate pope. After Urban deposed Joanna and put Louis's relative Charles of Durazzo on the throne of Naples, Louis helped Charles occupy the kingdom.

Louis joined a crusade against the pagan Lithuanians in December 1344. The crusaders – including John of Bohemia, Charles of Moravia, Peter of Bourbon, and William of Hainaut and Holland – laid siege to Vilnius. However, a Lithuanian invasion of the lands of the Teutonic Knights forced them to lift the siege. Louis returned to Hungary in late February 1345.

Louis dispatched Andrew Lackfi to invade the lands of the Golden Horde in retaliation for the Tatars' earlier plundering raids against Transylvania and the Szepesség (now Spiš in Slovakia). Lackfi and his army of mainly Székely warriors inflicted a defeat on a large Tatar army. Thereafter the Golden Horde's control of the lands between the Eastern Carpathians and the Black Sea weakened. 

While Louis's armies were fighting in Poland and against the Tatars, Louis marched to Croatia in June 1345 and besieged Knin, the former seat of the late Ivan Nelipac, who had successfully resisted Louis's father, forcing his widow and son to surrender. The counts of Corbavia and other Croatian noblemen also yielded to him during his stay in Croatia. The citizens of Zadar rebelled against the Republic of Venice and accepted his suzerainty.

While his envoys negotiated in Italy, Louis marched to Dalmatia to relieve Zadar, but the Venetians bribed his commanders. When the citizens broke out and attacked the besiegers on 1 July, the royal army failed to intervene, and the Venetians overcame the defenders outside the walls of the town. Louis withdrew but refused to renounce Dalmatia, although the Venetians offered to pay 320,000 golden florins as compensation. Lacking military support from Louis, however, Zadar surrendered to the Venetians on 21 December 1346.

Louis's brother Andrew was murdered in Aversa on 18 September 1345. Louis and his mother accused Queen Joanna I, Prince Robert of Taranto, Duke Charles of Durazzo, and other members of the Neapolitan branches of the Capetian House of Anjou of plotting against Andrew. In his letter of 15 January 1346 to Pope Clement VI, Louis demanded that the pope dethrone the "husband-killer" queen in favor of Charles Martel, her infant son by Andrew. Louis also laid claim to the regency of the kingdom during the minority of his nephew, referring to his patrilinear descent from the first-born son of Robert the Wise's father, Charles II of Naples. He even promised to increase the amount of yearly tribute that the kings of Naples would pay to the Holy See. After the pope failed to fully investigate Andrew's murder, Louis decided to invade southern Italy. In preparation for the invasion, he sent his envoys to Ancona and other Italian towns before summer 1346.

In November 1347, Louis set out for Naples with some 1,000 soldiers (Hungarians and Germans), mostly mercenaries. When he reached the border of Joanna’s kingdom, he had 2,000 Hungarian knights, 2,000 mercenary heavy cavalry, 2,000 Cuman horse archers, and 6,000 mercenary heavy infantry. He successfully avoided conflict in northern Italy, and his army was well-paid and disciplined. King Louis forbade plundering, and all supplies were bought from locals and paid for with gold. The Hungarian king marched across the land, announcing he was not going to fight any Italian cities or states, and thus was welcomed by most of them. Joanna in the meantime had married her cousin Louis of Taranto and had signed a peace with Naples' traditional enemy, the Kingdom of Sicily. The army of Naples, 2,700 knights and 5,000 infantrymen, was led by Louis of Taranto. At Foligno a papal legate asked Louis to renounce his enterprise, as the assassins had already been punished, and also in consideration of Naples' status as a papal fief. He did not relent, however, and before the end of the year he crossed the Neapolitan border without meeting any resistance.

Louis sent small expeditions one after one to Italy at the beginning of his war against Joanna, because he did not want to harass the Italians who had suffered from a famine the previous year. His first troops departed under the command of Nicholas Vásári, Bishop of Nyitra (now Nitra in Slovakia), on 24 April 1347. Louis also hired German mercenaries. He departed from Visegrád on 11 November. After marching through Udine, Verona, Modena, Bologna, Urbino, and Perugia, he entered the Kingdom of Naples on 24 December near L'Aquila, which had yielded to him.

The Battle of Capua was fought between 11–15 January 1348 between the troops of Louis I of Hungary and those of the Kingdom of Naples, in the course of the former's invasion of Naples.

After the collapse the Neapolitan mercenaries started to escape from Capua, forcing the commander of Capua to capitulate. Some days later Queen Joan sailed to Provence, followed by her husband; subsequently the Kingdom of Naples fell to King Louis.

Louis marched to Naples in February. The citizens offered him a ceremonious entry, but he refused, threatening to let his soldiers sack the town if they did not raise the taxes. He adopted the traditional titles of the kings of Naples – "King of Sicily and Jerusalem, Duke of Apulia and Prince of Capua" – and administered the kingdom from the Castel Nuovo, garrisoning his mercenaries in the most important forts. He used unusually brutal methods of investigation to capture all accomplices in the death of his brother, according to Domenico da Gravina. Most local noble families (including the Balzos and the Sanseverinos) refused to cooperate with him. The pope refused to confirm Louis's rule in Naples, which would have united two powerful kingdoms under Louis's rule. The pope and the cardinals declared Queen Joanna innocent of her husband's murder at a formal meeting of the College of Cardinals.

The Black Death reached Hungary in 1349. The first wave of the epidemic ended in June, but it returned in September, killing Louis's first wife, Margaret. Louis also fell ill, but survived the plague.

Although the Black Death was less devastating in the sparsely populated Hungary than in other parts of Europe, there were regions that became depopulated in 1349, and the demand for work force increased in the subsequent years. Indeed, colonization also continued in the 14th century. The new settlers mainly came from Moravia, Poland and other neighboring countries.

Louis proposed to renounce the Kingdom of Naples if Clement dethroned Joanna. After the pope refused, Louis departed for his second Neapolitan campaign in April 1350. He suppressed a mutiny that occurred among his mercenaries while he and his troops were waiting for the arrival of further troops in Barletta. While marching towards Naples, he faced resistance at many towns because his vanguards, which were under the command of Stephen Lackfi, had become notorious for their cruelty.

During the campaign, Louis personally led assaults and climbed city walls together with his soldiers, endangering his own life. While besieging Canosa di Puglia, Louis fell into the moat from a ladder when a defender of the fort hit him with a stone. He dove into a river without hesitation to save a young soldier who was swept away while exploring a ford upon his order. An arrow pierced Louis's left leg during the siege of Aversa. After the fall of Aversa to Hungarian troops on 3 August, Queen Joanna and her husband again fled from Naples. However, Louis decided to return to Hungary. According to the contemporaneous historian Matteo Villani, Louis attempted to "leave the kingdom without losing face" after he had run out of money and experienced the resistance of the local population.

Casimir III of Poland urged Louis to intervene in his war with the Lithuanians who had occupied Brest, Volodymyr-Volynskyi, and other important towns in Halych and Lodomeria in the previous years. The two monarchs agreed that Halych and Lodomeria would be integrated into the Kingdom of Hungary after Casimir's death. Louis led his army to Cracow in June 1351. Because Casimir fell ill, Louis became the sole commander of the united Polish and Hungarian army.

He invaded the lands of the Lithuanian prince, Kęstutis, in July. Kęstutis seemingly accepted Louis's suzerainty on 15 August and agreed to be baptised, along with his brothers, in Buda. However, Kęstutis did nothing to fulfill his promises after Polish and Hungarian troops were withdrawn. In an attempt to capture Kęstutis, Louis returned, but he could not defeat the Lithuanians, who even killed one of his allies, Boleslaus III of Płock, in battle. Louis returned to Buda before 13 September

Casimir III laid siege to Belz and Louis joined his uncle in March 1352. During the siege, which ended without the surrender of the fort, Louis was heavily injured in his head. Algirdas, Grand Duke of Lithuania, hired Tatar mercenaries who stormed into Podolia, Louis returned to Hungary because he feared a Tatar invasion of Transylvania. Pope Clement proclaimed a crusade against the Lithuanians and the Tatars in May, authorizing Louis to collect a tithe from Church revenues during the next four years.

The Neapolitans, who had quickly grown unhappy with the severe Hungarian rule, called back Joan, who paid for her return expedition (including the services of Urslingen's mercenaries) by selling her rights on Avignon to the popes. She landed near Naples and easily captured it, but the Hungarian commander Ulrich von Wolfurt commanded a strong resistance in Apulia.

When Urslingen deserted back to the Hungarians, she asked the Pope for help. The latter sent a legate who, after offering a great sum to Urslingen and the Wolfurt brothers, brokered a truce. Joanna and Louis would leave the Kingdom to await a new trial on Andrew's assassination, to be held in Avignon. The pope and the cardinals declared Queen Joanna innocent of her husband's murder at a formal meeting of the College of Cardinals in January 1352, and a peace treaty was signed with Hungary on March 23, 1352.

According to Matteo Villani, Louis launched an expedition against the Golden Horde at the head of an army of 200,000 horsemen in April 1354. The young Tatar ruler, whom historian Iván Bertényi identified as Jani Beg, did not want to wage war against Hungary and agreed to sign a peace treaty.

In summer 1356, Louis invaded Venetian territories without a formal declaration of war. He laid siege to Treviso on 27 July. A local nobleman, Giuliano Baldachino, noticed that Louis sat alone while writing his letters on the banks of Sile River on each morning. Baldachino proposed the Venetians to assassinate him in exchange for 12,000 golden florins and Castelfranco Veneto, but they refused his offer because he did not share the details of his plans with them. Louis returned to Buda in the autumn, but his troops continued the siege. Pope Innocent VI urged the Venetians to make a peace with Hungary.

Louis marched to Dalmatia in July 1357. Split, Trogir, and Šibenik soon got rid of Venetian governors and yielded to Louis. After a short siege, Louis's army also captured Zadar with the assistance of its townspeople. Tvrtko I of Bosnia, who had succeeded Louis's father-in-law in 1353, surrendered western Hum to Louis, who claimed that territory as his wife's dowry.

In the Treaty of Zadar, which was signed on 18 February 1358, the Republic of Venice renounced all Dalmatian towns and islands between the Gulf of Kvarner and Durazzo in favor of Louis. The Republic of Ragusa also accepted Louis's suzerainty. The Dalmatian towns remained self-governing communities, owing only a yearly tribute and naval service to Louis, who also abolished all commercial restrictions that had been introduced during the Venetians' rule. The merchants of Ragusa were explicitly entitled to freely trade in Serbia even during a war between Hungary and Serbia.

Religious fanaticism is one of the featuring element of Louis I's reign. He attempted, without success, to convert many of his Orthodox subjects to Catholicism by force. Louis decided to convert the Jews in Hungary to Catholicism around 1360. After experiencing resistance, he expelled them from his realms. Their immovable property was confiscated, but they were allowed to take their personal property with them and also to recover the loans they had made. No pogrom took place, which was unusual in Europe in the 14th century, according to historian Raphael Patai. Louis allowed the Jews to return to Hungary in 1364; legal proceedings between the Jews and those who had seized their houses lasted for years.

Louis invaded Bosnia from two directions in the spring of 1363. An army under the command of Palatine Nicholas Kont and Nicholas Apáti, Archbishop of Esztergom, laid siege to Srebrenica, but the fortress did not surrender. As the royal seal was stolen during the siege, a new seal was made and all Louis's former charters were to be confirmed with the new seal. The army under Louis's personal command besieged Sokolac in July, but could not capture it. Hungarian troops returned to Hungary in the same month.

Louis assembled his armies in Temesvár (now Timișoara in Romania) in February 1365. According to a royal charter that year, he was planning to invade Wallachia because the new voivode, Vladislav Vlaicu, had refused to obey him. However, he ended up heading a campaign against the Bulgarian Tsardom of Vidin and its ruler Ivan Sratsimir, which suggests that Vladislav Vlaicu had in the meantime yielded to him. Louis seized Vidin and imprisoned Ivan Stratsimir in May or June. Within three months, his troops occupied Ivan Stratsimir's realm, which was organized into a separate border province, or banate, under the command of Hungarian lords.

The Byzantine Emperor, John V Palaiologos visited Louis in Buda in early 1366, seeking his assistance against the Ottoman Turks, who had set foot in Europe. This was the first occasion that a Byzantine Emperor left his empire to plead for a foreign monarch's assistance. According to Louis's physician, Giovanni Conversini, at his first meeting with Louis, the emperor refused to dismount and to take off his hat, which offended Louis. John V pledged that he would promote the union of the Byzantine Church with the Papacy, and Louis promised to send him help, but neither the emperor nor Louis fulfilled their promises. Pope Urban encouraged Louis not to send help to Constantinople before the emperor guaranteed the Church union.

Casimir III of Poland died on 5 November 1370. Louis arrived after his uncle's funeral and ordered the erection of a splendid Gothic marble monument to the deceased king. He was crowned king of Poland in the Cracow Cathedral on 17 November. Casimir III had willed his patrimony – including the duchies of Sieradz, Łęczyca and Dobrzyń – to his grandson, Casimir IV, Duke of Pomerania. However, the Polish prelates and lords were opposed to the disintegration of Poland and Casimir III's testament was declared void. Louis visited Gniezno and made his Polish mother, Elizabeth, regent before returning to Hungary in December. His uncle's two surviving daughters (Anna and Jadwiga) accompanied him, and the Polish Crown Jewels were transferred to Buda, which raised discontent among Louis's new subjects. Louis's wife gave birth to a daughter, Catherine, in 1370, seventeen years after their marriage; a second daughter, Mary, was born in 1371. Thereafter Louis's made several attempts to safeguard his daughters' right to succeed him.

Louis invaded Wallachia in May 1375, because the new prince of Wallachia, Radu I, had formed an alliance with the Bulgarian ruler, Ivan Shishman, and the Ottoman Sultan Murad I. The Hungarian army routed the united forces of the Wallachians and their allies, and Louis occupied the Banate of Severin, but Radu I did not yield. During the summer, Wallachian troops stormed into Transylvania and Ottomans pillaged the Banat.

The Lithuanians made raids in Halych, Lodomeria, and Poland, almost reaching Cracow in November 1376. A riot broke out in Cracow against the unpopular queen mother, Elizabeth, on 6 December. The rioters slaughtered about 160 servants of the queen-mother, forcing her to flee to Hungary. Taking advantage of the situation, Władysław the White, Duke of Gniewkowo, who was a male member of the royal Piast dynasty, announced his claim to the Polish crown. However, Louis's partisans defeated the pretender, and Louis made him abbot of the Pannonhalma Archabbey in Hungary. Louis appointed Vladislaus II of Opole his governor in Poland.

In summer 1377, Louis invaded the territories held by the Lithuanian prince, George, in Lodomeria. His Polish troops soon captured Chełm, while Louis seized George's seat, Belz, after besieging it for seven weeks. He incorporated the occupied territories in Lodomeria, together with Galicia, into the Kingdom of Hungary. Three Lithuanian princes – Fedor, Prince of Ratno, and two princes of Podolia, Alexander and Boris – accepted Louis's suzerainty.

The cardinals who had turned against Pope Urban VI elected a new pope, Clement VII on 20 September 1378, which gave rise to the Western Schism. Louis acknowledged Urban VI as the legitimate pope and offered him support to fight against his opponents in Italy. As Joanna I of Naples decided to join Clement VII's camp, Pope Urban excommunicated and dethroned her on 17 June 1380. The pope acknowledged Charles of Durazzo, who had lived in Louis's court, as the lawful king of Naples. After Charles of Durazzo promised that he would not claim Hungary against Louis's daughters, Louis dispatched him to invade Southern Italy at the head of a large army. Within a year, Charles of Durazzo occupied the Kingdom of Naples, and forced Queen Joanna to surrender to him on 26 August 1381.

Louis, whose health was quickly deteriorating, invited the representatives of the Polish prelates and lord for a meeting in Zólyom. Upon his demand, the Poles swore loyalty to his daughter, Mary, and her fiancé, Sigismund of Luxemburg, on 25 July 1382. Louis died in Nagyszombat in the night on 10 or 11 September 1382.

Louis I was succeeded in 1382 by his daughter, Mary. However, most noblemen opposed the idea of being ruled by a female monarch. Taking advantage of the situation, a male member of the dynasty, Charles III of Naples claimed the throne for himself. He arrived in the kingdom in September 1385. It was not difficult for him to take power, as he gained the support of several Croatian lords and many contacts he made during his tenure as Duke of Croatia and Dalmatia. The Diet forced the queen to abdicate and elected Charles of Naples king. However, Elizabeth of Bosnia, widow of Louis and mother of Mary, arranged to have Charles assassinated on 7 February 1386. Paul Horvat, Bishop of Zagreb initiated a new rebellion and declared his infant son, Ladislaus of Naples king. They captured the queen in July 1386, but her supporters proposed the crown to her husband, Sigismund of Luxemburg. Queen Mary was soon liberated, but she never again intervened in the government.

Sigismund of Luxembourg married Queen Mary of Hungary in 1385 and was crowned King of Hungary soon after. He fought to restore and maintain authority to the throne. Mary died in 1395, leaving Sigismund the sole ruler of Hungary. In 1396, Sigismund led the Crusade of Nicopolis, but was decisively defeated by the Ottoman Empire. Afterwards, he founded the Order of the Dragon to fight the Turks and secured the thrones of Croatia, Germany and Bohemia. Sigismund was one of the driving forces behind the Council of Constance (1414–1418) that ended the Papal Schism, but which also led to the Hussite Wars that dominated the later period of his life. In 1433, Sigismund was crowned Holy Roman Emperor and ruled until his death in 1437.

Historian Thomas Brady Jr. remarks that Sigismund "possessed a breadth of vision and a sense of grandeur unseen in a German monarch since the thirteenth century". He realized the need to carry out reforms of the Empire and the Church at the same time. But external difficulties, self-inflicted mistakes and the extinction of the Luxembourg male line made this vision unfulfilled. 

Having raised money by pledging Brandenburg to his cousin Jobst, Margrave of Moravia (1388), he was engaged for the next nine years in a ceaseless struggle for the possession of this unstable throne. The central power was finally weakened to such an extent that only Sigismund's alliance with the powerful Czillei-Garai League could ensure his position on the throne. It was not for entirely selfless reasons that one of the leagues of barons helped him to power: Sigismund had to pay for the support of the lords by transferring a sizeable part of the royal properties. (For some years, the baron's council governed the country in the name of the Holy Crown). The restoration of the authority of the central administration took decades of work. The bulk of the nation headed by the House of Garai was with him; but in the southern provinces between the Sava and the Drava, the Horvathys with the support of King Tvrtko I of Bosnia, Mary's maternal uncle, proclaimed as their king Ladislaus of Naples, son of the murdered Charles II of Hungary. Not until 1395 did Nicholas II Garai succeed in suppressing them.

In 1396, Sigismund led the combined armies of Christendom against the Turks, who had taken advantage of the temporary helplessness of Hungary to extend their dominion to the banks of the Danube. This crusade, preached by Pope Boniface IX, was very popular in Hungary. The nobles flocked in their thousands to the royal standard, and were reinforced by volunteers from nearly every part of Europe. The most important contingent being that of the French led by John the Fearless, son of Philip II, Duke of Burgundy. Sigismund set out with 90,000 men and a flotilla of 70 galleys. After capturing Vidin, he camped with his Hungarian armies before the fortress of Nicopolis. Sultan Bayezid I raised the siege of Constantinople and, at the head of 140,000 men, completely defeated the Christian forces in the Battle of Nicopolis fought between the 25 and 28 September 1396. Sigismund returned by sea and through the realm of Zeta, where he ordained a local Montenegrin lord Đurađ II with the islands of Hvar and Korčula for resistance against the Turks; the islands were returned to Sigismund after Đurađ's death in April 1403. No new expedition was launched from Western Europe to stop the Turkish advance in the Balkans after this defeat, until the 1440s. 

The militia portalis, also known as peasant militia, was the first institution that secured the peasants' permanent participation in the defence of the Kingdom of Hungary. It was established when the Diet of Hungary obliged all landowners to equip one archer for 20 peasant plots on their estates to serve in the royal army in 1397. The unprofessional soldiers were to serve in the militia only during the emergency period.

After the disastrous Battle of Nicopolis, King Sigismund called for the Sabor in city of Križevci and issued a written guarantee (saluus conductus) stating he would not attempt personal revenge on the opponents or harm them in any way. But, he organised the killing of the Croatian Ban Stephen Lackfi (Stjepan Lacković) and his followers for supporting the opponent king candidate Ladislaus of Naples. The Croatian law dictated that no one could enter the Sabor with arms, so Ban Lackfi and his supporters left their arms in front of the church. Lackfi's supporting troops also remained outside the town. The king's supporters, on the other hand, were already in the church, fully armed. In the turbulent debate that followed, the king's supporters accused Lackfi for treason in the Battle of Nicopolis. Harsh words were used, fight started, and the king's vassals pulled their swords in front of the king, gutted Ban Lackfi, his nephew Stephen III Lackfi, who formerly served as Master of the horse, and the supporting nobility.

Bloody Sabor resulted in Sigismund's fear of the revenge of Lackfi's men, new rebellions of the nobles in Croatia and Bosnia, the death of 170 Bosnian nobles who were killed by Sigismund, and selling off Dalmatia to Venice for 100,000 ducats by Ladislaus of Naples. Finally, after 25 years of fighting, Sigismund succeeded in seizing power and was recognized as a king by means of giving privileges to the Croatian nobility.

In about 1406, Sigismund married Mary's cousin Barbara of Celje, daughter of Count Hermann II of Celje. Sigismund managed to establish control in Slavonia. He did not hesitate to use violent methods (see Bloody Sabor of Križevci), but from the river Sava to the south his control was weak. Sigismund personally led an army of almost 50,000 "crusaders" against the Bosnians, culminating with the Battle of Dobor in 1408, a massacre of about 200 noble families.

Sigismund founded his personal order of knights, the Order of the Dragon, after the victory at Dobor. The main goal of the order was fighting the Ottoman Empire. Members of the order were mostly his political allies and supporters. The main members of the order were Sigismund's close allies Nicholas II Garay, Hermann II of Celje, Stibor of Stiboricz, and Pippo Spano. The most important European monarchs became members of the order. He encouraged international trade by abolishing internal duties, regulating tariffs on foreign goods and standardizing weights and measures throughout the country.

From 1412 to 1423, Sigismund campaigned against the Republic of Venice in Italy. The king took advantage of the difficulties of Antipope John XXIII to obtain a promise that a council should be called in Constance in 1414 to settle the Western Schism. He took a leading part in the deliberations of this assembly, and during the sittings travelled to France, England, and Burgundy in a vain attempt to secure the abdication of the three rival popes. The council ended in 1418, having resolved the Schism and — of great consequence to Sigismund's future career — having the Czech religious reformer, Jan Hus, burned at the stake for heresy in July 1415. The complicity of Sigismund in the death of Hus is a matter of controversy. He had granted Hus a safe conduct and protested against his imprisonment; and Hus was burned during Sigismund's absence.

In 1419, the death of Wenceslaus IV left Sigismund titular King of Bohemia, but he had to wait for seventeen years before the Czech Estates would acknowledge him. Although the two dignities of King of the Romans and King of Bohemia added considerably to his importance, and indeed made him the nominal temporal head of Christendom, they conferred no increase of power and financially embarrassed him. Entrusting the government of Bohemia to Sofia of Bavaria, the widow of Wenceslaus, he hastened into Hungary.

The Bohemians, who distrusted him as the betrayer of Hus, were soon in arms; and the flame was fanned when Sigismund declared his intention of prosecuting the war against heretics. Three campaigns against the Hussites ended in disaster although the army of his most loyal ally Stibor of Stiboricz and later his son Stibor of Beckov could hold the Hussite side away from the borders of the Kingdom. The Turks were again attacking Hungary. The king, unable to obtain support from the German princes, was powerless in Bohemia. His attempts at the diet of Nuremberg in 1422 to raise a mercenary army were foiled by the resistance of the towns; and in 1424 the electors, among whom was Sigismund's former ally, Frederick I of Hohenzollern, sought to strengthen their own authority at the expense of the king. Although the scheme failed, the danger to Germany from the Hussites led to the Union of Bingen, which virtually deprived Sigismund of the leadership of the war and the headship of Germany.

The Battle of Kutná Hora (Kuttenberg) was an early battle and subsequent campaign in the Hussite Wars, fought on 21 December 1421 between German and Hungarian troops of the Holy Roman Empire and the Hussites, an early ecclesiastical reformist group that was founded in what is now the Czech Republic. In 1419, Pope Martin V declared a crusade against the Hussites. One branch of the Hussites, known as the Taborites, formed a religious-military community at Tábor. Under the leadership of the talented general Jan Žižka, the Taborites adopted the latest weaponry available, including handguns, long, thin cannons, nicknamed "snakes", and war wagons. Their adoption of the latter gave them the ability to fight a flexible and mobile style of warfare. Originally employed as a measure of last resort, its effectiveness against the royal cavalry turned field artillery into firm part of Hussite armies.

The Ottomans occupied Golubac Fortress in 1427 and started to regularly plunder the neighboring lands. The Ottoman raids forced many locals to depart for better protected regions. Their place was occupied by South Slavic refugees (mainly Serbs). Many of them were organized into mobile military units known as hussars.

On 30 May 1434, the Taborite army, led by Prokop the Great and Prokop the Lesser, who both fell in the battle, was totally defeated and almost annihilated at the Battle of Lipany. On 5 July 1436, the compacts were formally accepted and signed at Jihlava (Iglau), in Moravia, by King Sigismund, by the Hussite delegates, and by the representatives of the Roman Catholic Church. 

John Hunyadi was a leading Hungarian military and political figure in Central and Southeastern Europe during the 15th century. According to most contemporary sources, he was the member of a noble family of Wallachian ancestry. He mastered his military skills on the southern borderlands of the Kingdom of Hungary that were exposed to Ottoman attacks. Appointed voivode of Transylvania and head of a number of southern counties, he assumed responsibility for the defense of the frontiers in 1441.

He employed professional soldiers, but also mobilized local peasantry against invaders. These innovations contributed to his earliest successes against the Ottoman troops who were plundering the southern marches in the early 1440s. Although defeated in the battle of Varna in 1444 and in the second battle of Kosovo in 1448, his successful "Long Campaign" across the Balkan Mountains in 1443–44 and defence of Belgrade (Nándorfehérvár) in 1456, against troops led personally by the sultan, established his reputation as a great general. 

John Hunyadi was also an eminent statesman. He actively took part in the civil war between the partisans of Wladislas I and the minor Ladislaus V, two claimants to the throne of Hungary in the early 1440s, on behalf of the former. The Diet of Hungary elected Hunyadi as sole regent with the title of governor. Hunyadi's victories over the Turks prevented them from invading the Kingdom of Hungary for more than 60 years. His fame was a decisive factor in the election of his son, Matthias Corvinus, as king by the Diet of 1457. Hunyadi is a popular historical figure among Hungarians, Romanians, Serbs, Bulgarians and other nations of the region.

Sigismund's active foreign policy demanded new sources of income. For instance, the king imposed "extraordinary" taxes on the prelates and mortgaged 13 Saxon towns in the Szepesség to Poland in 1412. He regularly debased coinage which resulted in a major rebellion of Hungarian and Romanian peasants in Transylvania in 1437. It was suppressed by the joint forces of the Hungarian noblemen, Székelys and Transylvanian Saxons who concluded an agreement against the rebels.

The Ottomans had occupied the larger part of Serbia by the end of 1438. In the same year, Ottoman troops—supported by Vlad II Dracul, Prince of Wallachia—made an incursion into Transylvania, plundering Hermannstadt/Nagyszeben, Gyulafehérvár (present-day Alba Iulia, Romania) and other towns. After the Ottomans laid siege to Smederevo, the last important Serbian stronghold in June 1439, Đurađ Branković, Despot of Serbia fled to Hungary to seek military assistance.

King Albert died of dysentery on 27 October 1439. His widow, Elisabeth—Emperor Sigismund's daughter—gave birth to a posthumus son, Ladislaus. The Estates of the realm offered the crown to Vladislaus, King of Poland, but Elizabeth had his infant son crowned king on 15 May 1440. However, Vladislaus accepted the Estates' offer and was also crowned king on 17 July. During the ensuing civil war between the two kings' partisans, Hunyadi supported Vladislaus. Hunyadi fought against the Ottomans in Wallachia, for which King Vladislaus granted him five domains in the vicinity of his family estates on 9 August 1440.

Hunyadi, together with Nicholas of Ilok, annihilated the troops of Vladislaus' opponents at Bátaszék at the very beginning of 1441.Their victory effectively put an end to the civil war. The grateful King appointed Hunyadi and his comrade joint Voivodes of Transylvania and Counts of the Székelys in February. In short, the King also nominated them Ispáns of Temes County and conferred upon them the command of Belgrade and all other castles along the Danube.

Hunyadi set about repairing the walls of Belgrade, which had been damaged during an Ottoman attack. In retaliation for Ottoman raids in the region of the river Sava, he made an incursion into Ottoman territory in the summer or autumn of 1441. He scored a pitched battle victory over Ishak Bey, the commander of Smederovo.

The Ottoman Sultan, Murad II, proclaimed in the autumn of 1441 that a raid into Hungarian Transylvania would take place in March 1442. In early March 1442, the marcher lord Mezid Bey led 16,000 akinji cavalry raiders into Transylvania, crossing the Danube to Wallachia at Nicopolis and marching north in formation.

John Hunyadi was taken by surprise and lost the first battle near Marosszentimre (Sântimbru, Romania).Bey Mezid lay siege to Hermannstadt, but the united forces of Hunyadi and Újlaki, who had in the meantime arrived in Transylvania, forced the Ottomans to lift the siege. The Ottoman forces were annihilated. This was Hunyadi's third victory over the Ottomans after the relief of Smederevo in 1437 and the defeat of Ishak Beg midway between Semendria and Belgrade in 1441.

Pope Eugenius IV, who had been an enthusiastic propagator of a new crusade against the Ottomans, sent his legate, Cardinal Giuliano Cesarini to Hungary. The Cardinal arrived in May 1442 tasked with mediating a peace treaty between King Vladislaus and Dowager Queen Elisabeth.

The Ottoman Sultan, Murad II dispatched Şihabeddin Pasha—the governor of Rumelia—to invade Transylvania with a force of 70,000. The Pasha stated that the mere sight of his turban would force his enemies to run far away. Although Hunyadi could only muster a force of 15,000 men, he inflicted a crushing defeat on the Ottomans at the Ialomița River in September. Hunyadi placed Basarab II on the princely throne of Wallachia, but Basarab's opponent Vlad Dracul returned and forced Basarab to flee in early 1443.

In April 1443 King Vladislaus and his barons decided to mount a major campaign against the Ottoman Empire. With the mediation of Cardinal Cesarini, Vladislaus reached a truce with Frederick III of Germany, who had been the guardian of the child Ladislaus V. The armistice guaranteed that Frederick III would not attack Hungary in the subsequent twelve months.

Spending around 32,000 gold florins from his own treasury, Hunyadi hired more than 10,000 mercenaries. The King also mustered troops, and reinforcements arrived from Poland and Moldavia. The King and Hunyadi departed for the campaign at the head of an army of 25–27,000 men in the autumn of 1443. In theory, Vladislaus commanded the army, but the true leader of the campaign was Hunyadi. Despot Đurađ Branković joined them with a force of 8,000 men.

Hunyadi commanded the vanguards and routed four smaller Ottoman forces, hindering their unification. He captured Kruševac, Niš and Sofia. However, the Hungarian troops could not break through the passes of the Balkan Mountains towards Edirne. Cold weather and the lack of supplies forced the Christian troops to stop the campaign at Zlatitsa. After being victorious in the Battle of Kunovica, they returned to Belgrade in January and Buda in February 1444.

The Battle of Niš (early November, 1443) saw crusaders led by John Hunyadi and Đurađ Branković capture the Ottoman stronghold of Niš in Serbia, and defeat three armies of the Ottoman Empire. The Battle of Niš was part of Hunyadi's expedition known as the long campaign. Hunyadi, at the head of the vanguard, crossed the Balkans through the Gate of Trajan, captured Niš, defeated three Turkish pashas, and after taking Sofia, united with the royal army and defeated Sultan Murad II at Snaim (Kustinitza). The impatience of the king and the severity of the winter then compelled him (in February 1444) to return home.

The Battle of Zlatitsa was fought on 12 December 1443 between the Ottoman Empire and Serbian Hungarian troops in the Balkans. The battle was fought at Zlatitsa Pass near the town of Zlatitsa in the Balkan Mountains, Ottoman Empire (modern-day Bulgaria). The impatience of the king of Poland and the severity of the winter then compelled Hunyadi (February 1444) to return home, but not before he had utterly broken the Sultan's power in Bosnia, Herzegovina, Serbia, Bulgaria, and Albania.

The Christian contingent began their retreat on 24 December 1443, after the Battle of Zlatica. The Ottoman forces followed them across the rivers Iskar and Nišava and in the Kunorica pass attacked (some sources say ambushed by) the rear flanks of the retreating armies composed of armies of the Serbian Despotate under command of Đurađ Branković. The battle took place during the night, under the full moon. Hunyadi and Władysław who were already through the pass left their supplies guarded by infantry and attacked Ottoman forces near the river on the eastern side of the mountain. The Ottomans were defeated and many Ottoman commanders, including Mahmud Çelebi of Çandarlı family (in some earlier sources referred to as Karambeg), were captured.

The Ottoman defeat in the Battle of Kunovica and capture of Mahmud Bey, the Sultan's son-in-law, created the impression of an overall victorious campaign. According to some sources, Skanderbeg participated in this battle on the Ottoman side and deserted Ottoman forces during the conflict.

Anticipating an Ottoman invasion encouraged by the young and inexperienced new Ottoman sultan, Hungary co-operated with Venice and Pope Eugene IV to organize a new crusader army led by Hunyadi and Władysław III. On receipt of this news, Mehmet II understood that he was too young and inexperienced to successfully fight the coalition. He recalled Murad II to the throne to lead the army into battle, but Murad II refused. Angry at his father, who had long since retired to a contemplative life in southwestern Anatolia, Mehmed II wrote, "If you are the Sultan, come and lead your armies. If I am the Sultan I hereby order you to come and lead my armies." It was only after receiving this letter that Murad II agreed to lead the Ottoman army.

During the battle, the young king, ignoring Hunyadi's advice, rushed 500 of his Polish knights against the Ottoman center. They attempted to overrun the Janissary infantry and take Murad prisoner, and almost succeeded, but in front of Murad's tent Władysław's horse either fell into a trap or was stabbed, and the king was slain by mercenary Kodja Hazar, who beheaded him while doing so. The remaining coalition cavalry were demoralized and defeated by the Ottomans. Hunyadi narrowly escaped from the battlefield, but was captured and imprisoned by Wallachian soldiers. However, Vlad Dracul set him free before long.

At the next Diet of Hungary, which assembled in April 1445, the Estates decided that they would unanimously acknowledge the child Ladislaus V's rule if King Vladislaus, whose fate was still uncertain, had not arrived in Hungary by the end of May. The Estates also elected seven "Captains in Chief", including Hunyadi, each being responsible for the restoration of internal order in the territory allotted to them. Hunyadi was assigned to administer the lands east of the river Tisza. Here he possessed at least six castles and owned lands in about ten counties, which made him the most powerful baron in the region under his rule.

Hunyadi invaded Wallachia and dethroned Vlad Dracul in December 1447. He installed his cousin Vladislav on the throne.

The Second Battle of Kosovo was the culmination of a Hungarian offensive to avenge the defeat at Varna four years earlier. In the three-day battle the Ottoman army under the command of Sultan Murad II defeated the Crusader army of regent John Hunyadi. After that battle, the path was clear for the Turks to conquer Serbia and the other Balkan States, it also ended any hopes of saving Constantinople. The Hungarian kingdom no longer had the military and financial resources to mount an offensive against the Ottomans. With the end of the half-century-long Crusader threat to their European frontier, Murad's son Mehmed II was free to lay siege to Constantinople in 1453.

After the fall of Constantinople in 1453, the Ottoman Sultan Mehmed the Conqueror rallied his resources to subjugate the Kingdom of Hungary. His immediate objective was the border fort of the town of Belgrade (Hungarian: Nándorfehérvár). John Hunyadi, the Count of Temes and captain-general of Hungary, who had fought many battles against the Turks in the previous two decades, prepared the defenses of the fortress.

The siege escalated into a major battle, during which Hunyadi led a sudden counterattack that overran the Ottoman camp, ultimately compelling the wounded Mehmed II to lift the siege and retreat. The battle had significant consequences, as it stabilized the southern frontiers of the Kingdom of Hungary for more than half a century and thus considerably delayed the Ottoman advance in Europe.

As he had previously ordered all Catholic kingdoms to pray for the victory of the defenders of Belgrade, the Pope celebrated the victory by making an enactment to commemorate the day. This led to the legend that the noon bell ritual undertaken in Catholic and old Protestant churches, enacted by the Pope before the battle, was founded to commemorate the victory. The day of the victory, July 22, has been a memorial day in Hungary ever since.

The crusaders' victory at Belgrade over the Sultan who had conquered Constantinople generated enthusiasm throughout Europe. Processions to celebrate Hunyadi's triumph were made in Venice and Oxford. However, in the crusaders' camp unrest was growing, because the peasants denied that the barons had played any role in the victory. In order to avoid an open rebellion, Hunyadi and Capistrano disbanded the crusaders' army.

Meanwhile, a plague had broken out and killed many people in the crusaders' camp. Hunyadi was also taken ill and died near Zimony (present-day Zemun, Serbia) on 11 August. 

The Black Army is a common name given to the military forces serving under the reign of King Matthias Corvinus of Hungary. The ancestor and core of this early standing mercenary army appeared in the era of his father John Hunyadi in the early 1440s. The idea of the professional standing mercenary army came from Matthias' juvenile readings about the life of Julius Caesar.

Hungary's Black Army traditionally encompasses the years from 1458 to 1494. The mercenary soldiers of other countries in the era were conscripted from the general population at times of crisis, and soldiers worked as bakers, farmers, brick-makers, etc. for most of the year. In contrast, the men of the Black Army fought as well-paid, full-time mercenaries and were purely devoted to the arts of warfare. It was a standing mercenary army that conquered large parts of Austria (including the capital Vienna in 1485) and more than half of the Crown of Bohemia (Moravia, Silesia and both Lusatias), the other important victory of the army was won against the Ottomans at the Battle of Breadfield in 1479.

King Matthias waged wars against the Czech mercenaries who dominated Upper Hungary (today parts of Slovakia and Northern Hungary) and against Frederick III, Holy Roman Emperor, who claimed Hungary for himself. In this period, the Ottoman Empire conquered Serbia and Bosnia, terminating the zone of buffer states along the southern frontiers of the Kingdom of Hungary. Matthias signed a peace treaty with Frederick III in 1463, acknowledging the Emperor's right to style himself King of Hungary. 

Matthias introduced new taxes and regularly set taxation at extraordinary levels. These measures caused a rebellion in Transylvania in 1467, but he subdued the rebels. The next year, Matthias declared war on George of Poděbrady, the Hussite King of Bohemia, and conquered Moravia, Silesia, and Lausitz, but he could not occupy Bohemia proper. The Catholic Estates proclaimed him King of Bohemia on 3 May 1469, but the Hussite lords refused to yield to him even after the death of their leader George of Poděbrady in 1471.

Matthias established one of the earliest professional standing armies of medieval Europe (the Black Army of Hungary), reformed the administration of justice, reduced the power of the barons, and promoted the careers of talented individuals chosen for their abilities rather than their social statuses. Matthias patronized art and science; his royal library, the Bibliotheca Corviniana, was one of the largest collections of books in Europe. With his patronage, Hungary became the first country to embrace the Renaissance from Italy. As Matthias the Just, the monarch who wandered among his subjects in disguise, he remains a popular hero of Hungarian and Slovak folk tales.

The young monarch in short time removed the powerful Ladislaus Garay from the office of palatine and his uncle, Michael Szilágyi, of the regency. Led by Garay, his opponents offered the crown to Frederick III, but Matthias defeated them and concluded a peace treaty with the emperor in 1464.

At the Diet of March 1467, two traditional taxes were renamed; the chamber's profit was thereafter collected as tax of the royal treasury and the thirtieth as the Crown's customs. Because of this change, all previous tax exemptions became void, increasing state revenues. Matthias set about centralizing the administration of royal revenues. He entrusted the administration of the Crown's customs to John Ernuszt, a converted Jewish merchant. Within two years, Ernuszt was responsible for the collection of all ordinary and extraordinary taxes, and the management of the salt mines.

Matthias's tax reform caused a revolt in Transylvania. The representatives of the "Three Nations" of the province—the noblemen, the Saxons and the Székelys—formed an alliance against the King in Kolozsmonostor (now Mănăștur district in Cluj-Napoca, Romania) on 18 August, stating that they were willing to fight for the freedom of Hungary. Matthias assembled his troops immediately and hastened to the province. The rebels surrendered without resistance but Matthias severely punished their leaders, many of whom were impaled, beheaded, or mercilessly tortured upon his orders. Suspecting that Stephen the Great had supported the rebellion, Matthias invaded Moldavia. However, Stephen's forces routed Matthias's at the Battle of Baia on 15 December 1467. Matthias suffered severe injuries, forcing him to return to Hungary.

The Battle of Baia was the last Hungarian attempt to subdue Moldavia, as previous attempts had ended in failure. Matthias Corvinus invaded Moldavia as a consequence of Stephen's annexation of Chilia—a fortress and harbour on the coast of the Black Sea—from Hungarian and Wallachian forces. It had belonged to Moldavia centuries earlier. The battle was a Moldavian victory, whose outcome ended Hungarian claims on Moldavia.

The Bohemian War (1468–1478) began when the Kingdom of Bohemia was invaded by the king of Hungary, Matthias Corvinus. Matthias invaded with the pretext of returning Bohemia to Catholicism; at the time, it was ruled by the Hussite king, George of Poděbrady. Matthias' invasion was largely successful, leading to his acquisition of the southern and eastern parts of the country. Its core lands however, centered on Prague, were never taken. Ultimately both Matthias and George would proclaim themselves king, though neither ever acquired all the necessary subordinate titles. When George died in 1471, his successor Vladislaus II continued the fight against Matthias. In 1478, the war ended following the treaties of Brno and the Olomouc. Upon Matthias' death in 1490, Vladislaus would succeed him as king of both Hungary and Bohemia.

The Austrian–Hungarian War was a military conflict between the Kingdom of Hungary under Mathias Corvinus and the Habsburg Archduchy of Austria under Frederick V (also Holy Roman Emperor as Frederick III). The war lasted from 1477 to 1488 and resulted in significant gains for Matthias, which humiliated Frederick, but which were reversed upon Matthias' sudden death in 1490.

Matthias was the first non-Italian monarch promoting the spread of Renaissance style in his realm. His marriage to Beatrice of Naples strengthened the influence of contemporaneous Italian art and scholarship, and it was under his reign that Hungary became the first land outside Italy to embrace the Renaissance. The earliest appearance of Renaissance style buildings and works outside Italy were in Hungary. The Italian scholar Marsilio Ficino introduced Matthias to Plato's ideas of a philosopher-king uniting wisdom and strength in himself, which fascinated Matthias. Matthias is the main character in Aurelio Lippo Brandolini's Republics and Kingdoms Compared, a dialogue on the comparison of the two forms of government. According to Brandolini, Matthias said a monarch "is at the head of the law and rules over it" when summing up his own concepts of state.

Matthias also cultivated traditional art. Hungarian epic poems and lyric songs were often sung at his court. He was proud of his role as the defender of Roman Catholicism against the Ottomans and the Hussites. He initiated theological debates, for instance on the doctrine of the Immaculate Conception, and surpassed both the Pope and his legate "with regard to religious observance", according to the latter. Matthias issued coins in the 1460s bearing an image of the Virgin Mary, demonstrating his special devotion to her cult.

Upon Matthias's initiative, Archbishop John Vitéz and Bishop Janus Pannonius persuaded Pope Paul II to authorize them to set up a university in Pressburg (now Bratislava in Slovakia) on 29 May 1465. The Academia Istropolitana was closed shortly after the Archbishop's death. Matthias was contemplating establishing a new university in Buda but this plan was not accomplished.

Decline (1490–1526)

The Ottoman army entered Transylvania on October 9, near Kelnek (Câlnic), led by Ali Koca Bey. The Akıncıs attacked a few villages, homesteads, and market towns, taking a number of Hungarians, Vlachs, and Saxons captive. On October 13, Koca Bey set up his camp in the Breadfield (Kenyérmező), near Zsibót. Koca Bey was obliged into the campaign by the insistence of Basarab cel Tânăr, a Wallachian prince, who himself brought 1,000–2,000 infantry to the cause.

The battle commenced in the afternoon. Stephen V Báthory, the Voivode of Transylvania, fell from his horse and the Ottomans nearly captured him, but a nobleman called Antal Nagy whisked the voivode away. Having joined battle, the Ottomans were in ascendancy early on, but Kinizsi charged against the Turks with the Hungarian heavy cavalry and 900 Serbs under Jakšić assisted by "numerous courtiers of the king". Ali Bey was forced to retreat. Kinizsi moved laterally to vigorously smash the Turkish center and before long Isa Bey also withdrew. The few Turks who survived the massacre fled into the mountains, where the majority were killed by the local men. The hero of the battle was Pál Kinizsi, the legendary Hungarian general and a man of Herculean strength in the service of Matthias Corvinus' Black Army of Hungary.

The Battle of Leitzersdorf was a battle between the Holy Roman Empire and the Kingdom of Hungary in 1484. Fuelled by the earlier conflicts of Matthias Corvinus and Frederick III, Holy Roman Emperor. It marked the end of anti-Ottoman preparations and initiations of a holy war. It was the only open field battle of the Austro-Hungarian War, and the defeat meant – in long terms – the loss of the Archduchy of Austria for the Holy Roman Empire.

The siege of Vienna was a decisive siege in 1485 of the Austrian–Hungarian War. It was a consequence of the ongoing conflict between Frederick III and Matthias Corvinus. The fall of Vienna meant that it merged with Hungary from 1485 to 1490. Matthias Corvinus also moved his royal court to the newly occupied city. Vienna became for more than a decade the capital of Hungary.

Vladislaus laid claim to Hungary after Matthias's death. The Diet of Hungary elected him king after his supporters defeated John Corvinus. The other two claimants, Maximilian of Habsburg and Vladislaus's brother, John Albert, invaded Hungary, but they could not assert their claim and made peace with Vladislaus in 1491. He settled in Buda, enabling the Estates of Bohemia, Moravia, Silesia and both Lusatias to take full charge of state administration. Like previously in Bohemia, also in Hungary Vladislaus always approved the decisions of the Royal Council, hence his Hungarian nickname "Dobzse László" (from Czech král Dobře, in Latin rex Bene – "King Very Well"). Due to the concessions he had made before his election, the royal treasury could not finance a standing army and Matthias Corvinus's Black Army was dissolved after a rebellion, although the Ottomans made regular raids against the southern border and after 1493 even annexed territories in Croatia.

During his reign, the Hungarian royal power declined in favour of the Hungarian magnates, who used their power to curtail the peasants’ freedom. His reign in Hungary was largely stable, although Hungary was under consistent border pressure from the Ottoman Empire and went through the revolt of György Dózsa. On March 11, 1500, the Bohemian Diet adopted a new land constitution that limited royal power, and Vladislav signed it in 1502. Additionally, he oversaw the construction (1493–1502) of the enormous Vladislav Hall atop the palace at the Prague Castle.

Vladislaus had inherited an almost empty treasury from Matthias and he was unable to raise money to finance his predecessor's Black Army (a standing army of mercenaries). The unpaid mercenaries rose up and pillaged several villages along the Sava River. Paul Kinizsi routed them in September. Most mercenaries were executed and Vladislaus dissolved the remnants of the army on 3 January 1493.

In 1514, the Hungarian chancellor, Tamás Bakócz, returned from the Holy See with a papal bull issued by Leo X authorising a crusade against the Ottomans. He appointed Dózsa to organize and direct the movement. Within a few weeks, Dózsa had gathered an army of some 40,000 so-called hajdúta, consisting for the most part of peasants, wandering students, friars, and parish priests - some of the lowest-ranking groups of medieval society. 

The volunteers became increasingly angry at the failure of the nobility to provide military leadership (the original and primary function of the nobility and the justification for its higher status in the society.) The rebellious, anti-landlord sentiment of these "Crusaders" became apparent during their march across the Great Hungarian Plain, and Bakócz cancelled the campaign. The movement was thus diverted from its original object, and the peasants and their leaders began a war of vengeance against the landlords. The rebellion spread quickly, principally in the central or purely Magyar provinces, where hundreds of manor houses and castles were burnt and thousands of the gentry killed by impalement, crucifixion, and other methods. Dózsa's camp at Cegléd was the centre of the jacquerie, as all raids in the surrounding area started out from there.

As his suppression had become a political necessity, Dózsa was routed at Temesvár (today Timișoara, Romania) by an army of 20,000 led by John Zápolya and István Báthory. He was captured after the battle, and condemned to sit on a smouldering, heated iron throne, and forced to wear a heated iron crown and sceptre (mocking his ambition to be king). The revolt was repressed but some 70,000 peasants were tortured. György's execution, and the brutal suppression of the peasants, greatly aided the 1526 Ottoman invasion as the Hungarians were no longer a politically united people. 

Louis II (Czech: Ludvík, Croatian: Ludovik, Hungarian: Lajos, Slovak: Ľudovít; 1 July 1506 – 29 August 1526) was King of Hungary, Croatia and Bohemia from 1516 to 1526. He was killed during the Battle of Mohács fighting the Ottomans, whose victory led to the Ottoman annexation of large parts of Hungary.

Following the accession to the throne of Suleiman I, the sultan sent an ambassador to Louis II to collect the annual tribute that Hungary had been subjected to. Louis refused to pay the annual tribute and had the Ottoman ambassador executed and sent the head to the Sultan. Louis believed that the Papal States and other Christian States including Charles V, Holy Roman Emperor would help him. This event hastened the fall of Hungary.

Hungary was in a state of near anarchy in 1520 under the rule of the magnates. The king's finances were a shambles; he borrowed to meet his household expenses despite the fact that they totaled about one-third of the national income. The country's defenses weakened as border guards went unpaid, fortresses fell into disrepair, and initiatives to increase taxes to reinforce defenses were stifled. In 1521 Sultan Suleiman the Magnificent was well aware of Hungary's weakness.

The Ottoman Empire declared war on the Kingdom of Hungary, Suleiman postponed his plan to besiege Rhodes and made an expedition to Belgrade. Louis and his wife Mary requested military aid from other European countries. His uncle, King Sigismund of Poland, and his brother-in-law, Archduke Ferdinand, were willing to help. Ferdinand dispatched 3,000 infantry troops and some artillery while preparing to mobilize the Austrian estates, while Sigismund promised to send footmen. The coordination process totally failed though. Mary, although a determined leader, caused distrust by relying on non-Hungarian advisors while Louis lacked vigour, which his nobles realized.

Belgrade and many strategic castles in Serbia were captured by the Ottomans. This was disastrous for Louis' kingdom; without the strategically important cities of Belgrade and Šabac, Hungary, including Buda, was open to further Turkish conquests.

After the siege of Rhodes, in 1526 Suleiman made a second expedition to subdue all of Hungary. Around the middle of July, the young King departed from Buda, determined to "either fight back the invaders or be crushed once and for all". Louis made a tactical error when he tried to stop the Ottoman army in an open field battle with a medieval army, insufficient firearms, and obsolete tactics. On 29 August 1526, Louis led his forces against Suleiman in the disastrous Battle of Mohács. The Hungarian army was surrounded by Ottoman cavalry in a pincer movement, and in the center the Hungarian heavy knights and infantry were repulsed and suffered heavy casualties, especially from the well-positioned Ottoman cannons and well-armed and trained Janissary musketeers.

Nearly the entire Hungarian Royal army was destroyed in nearly 2 hours on the battlefield. During the retreat, the twenty-year-old king died when he fell backwards off his horse while trying to ride up a steep ravine of the Csele stream. He fell into the stream and, due to the weight of his armor, he was unable to stand up and drowned. As Louis had no legitimate children, Ferdinand was elected as his successor in the Kingdoms of Bohemia and Hungary, but the Hungarian throne was contested by John Zápolya, who ruled the areas of the kingdom conquered by the Turks as an Ottoman client.