Sengoku Jidai

During this period, although the Emperor of Japan was officially the ruler of his nation and every lord swore loyalty to him, he was largely a marginalized, ceremonial, and religious figure who delegated power to the shōgun, a noble who was roughly equivalent to a general. In the years preceding this era, the shogunate gradually lost influence and control over the daimyōs (local lords). Many of these lords began to fight uncontrollably with each other for control over land and influence over the shogunate.

A dispute between Hosokawa Katsumoto and Yamana Sōzen escalated into a nationwide civil war involving the Ashikaga shogunate and a number of daimyō in many regions of Japan. The war initiated the Sengoku period, "the Warring States period". This period was a long, drawn-out struggle for domination by individual daimyō, resulting in a mass power-struggle between the various houses to dominate the whole of Japan.

After the Ōnin War, the Ashikaga bakufu completely fell apart; for all practical purposes, the Hosokawa family was in charge and the Ashikaga shōguns became their puppets. The Hosokawa family controlled the shogunate until 1558 when they were betrayed by a vassal family, the Miyoshi. The powerful Ōuchi were also destroyed by a vassal, Mōri Motonari, in 1551. Kyoto was devastated by the war, not really recovering until the mid-16th century.

The Kaga Rebellion or Chōkyō Uprising was a large-scale revolt in Kaga Province (present-day southern Ishikawa Prefecture), Japan, in late 1487 through 1488. Togashi Masachika, who ruled Kaga Province as shugo, had been restored to power in 1473 with aid from the Asakura clan as well as the Ikkō-ikki, a loose collection of lesser nobility, monks, and farmers. By 1474, however, the Ikkō-ikki grew discontent with Masachika, and launched some initial revolts, which were easily quelled. In 1487, when Masachika left on a military campaign, between 100,000 and 200,000 Ikkō-ikki revolted. Masachika returned with his army, but the Ikkō-ikki, backed by several disaffected vassal families, overwhelmed his army and surrounded him in his palace, where he committed seppuku. The former vassals of Masachika granted the position of shugo to Masachika's uncle Yasutaka, but over the next several decades, the Ikkō-ikki increased their political hold on the province, which they would effectively control for almost a century.

During the 15th century in Japan, peasant revolts, known as ikki, became much more commonplace. During the turmoil of the Ōnin War (1467–1477) and subsequent years, these rebellions increased in both frequency and success. Many of these rebels became known as Ikkō-ikki, a collection of peasant farmers, Buddhist monks, Shinto priests, and jizamurai (lesser nobles) who all espoused belief in the Jōdo Shinshū sect of Buddhism. Rennyo, the Hongan-ji abbot who led the Jōdo Shinshū movement, attracted a large following in Kaga and Echizen Province, but distanced himself from the political goals of the ikki, advocating violence only for self-defense or defense of one's religion.During the mid-15th century, a civil war broke out among the Togashi clan over the position of shugo.

He gained control of Izu Province in 1493, avenging a wrong committed by a member of the Ashikaga family which held the shogunate. With Sōun's successful invasion in Izu province, he is credited by most historians as being the first "Sengoku daimyō". After building a stronghold at Nirayama, Hōjō Sōun secured Odawara Castle in 1494, the castle which would become the center of the Hōjō family's domains for nearly a century. In an act of treachery, he seized the castle after arranging for its lord to be murdered while out hunting.

Following the fall of the Ashikaga shogunate, which was based in Kyoto, control of the city, and thus ostensibly the country, fell into the hands of the Hosokawa clan (who held the post of Kyoto Kanrei – Shōgun's deputy in Kyoto) for a few generations.

Katsumoto's son, Hosokawa Masamoto, held power in this way at the end of the 15th century, but was assassinated by Kōzai Motonaga and Yakushiji Nagatada in 1507. After his death, the clan became divided and was weakened by internecine fighting. What power they still had, however, was centered in and around Kyoto. This gave them the leverage to consolidate their power to some extent, and came to be strong rivals with the Ōuchi clan, both politically, and in terms of dominating trade with China.

Harumoto succeeded to a house at the age of seven, after his father's death in 1520. While still a minor, he was supported by his caretaker Miyoshi Motonaga. In 1531, Harumoto defeats Hosokawa Takakuni. He feared Motonaga who had got credit and killed him next year. After that, Harumoto ruled the whole area of Kinai (Yamashiro Province, Yamato Province, Kawachi Province, Izumi Province and Settsu Province) and took hold of the Ashikaga shogunate as the Kanrei.

The battle took place seven days after the murder of Matsudaira leader Kiyoyasu (grandfather of Tokugawa Ieyasu) at the hands of his vassal Abe Masatoyo. The forces of Matsudaira set out to take revenge against the rebel Masatoyo and his army, and were victorious.

The Portuguese land on Tanegashima, becoming the first Europeans to arrive in Japan, and introduce the arquebus into Japanese warfare. This period of time is often entitled Nanban trade, where both Europeans and Asians would engage in mercantilism.

This was part of a failed attempt by the Uesugi clan to regain Kawagoe Castle from the Later Hōjō clan. This Hōjō victory marked the decisive turning point in the struggle for the Kanto region. The Hōjō tactics which said to be "the one of the most notable examples of night fighting in samurai history". This defeat for the Uesugi would lead to the near-extinction of the family, and with Tomosada's death, the Ōgigayatsu branch came to an end.

In 1543, Hosokawa Ujitsuna who was the foster son of Takakuni, raised his armies, and in 1549, Miyoshi Nagayoshi who was a dominant retainer and the first son of Motonaga betrayed Harumoto and took side with Ujitsuna. Because of that, Harumoto was defeated. After Hosokawa Harumoto's fall, Miyoshi Nagayoshi and the Miyoshi clan would experience a great rise of power, and engage in a protracted military campaign against the Rokkaku and the Hosokawa. Harumoto, Ashikaga Yoshiteru who was the 13th Ashikaga shōgun and Ashikaga Yoshiharu who was the father of Yoshiteru were purged to Ōmi Province.

The Tainei-ji incident was a coup in September 1551 by Sue Takafusa (later known as Sue Harukata) against Ōuchi Yoshitaka, hegemon daimyō of western Japan, which ended in the latter's forced suicide in Tainei-ji, a temple in Nagato Province. The coup put an abrupt end to the prosperity of the Ōuchi clan, though they ruled western Japan in name for another six years under the figurehead Ōuchi Yoshinaga, who was not related to the Ōuchi by blood.

The downfall of the Ōuchi had far-reaching consequence beyond western Honshu. Since the courtiers in Yamaguchi were slaughtered, the imperial court in Kyoto became at the mercy of Miyoshi Nagayoshi. Warriors across Japan no longer ruled through the court but only used it to confer legitimacy. The once-peaceful Ōuchi territories in northern Kyushu descended into warfare among the Ōtomo, the Shimazu, and the Ryūzōji, who struggled to fill the void. The Ōtomo came to control much of these former Ōuchi domains in northern Kyushu, and their city of Funai flourished as a new centre of trade after the fall of Yamaguchi. At sea, foreign trade with China also suffered. The Ōuchi had been the official handlers of the Japan-China trade, but the Ming Chinese refused to acknowledge the usurpers and cut off all official trade between the two countries. Clandestine trade and piracy replaced the official trade of the Ōuchi, as the Ōtomo, the Sagara, and the Shimazu vied with each other to send ships to China. In the end, it was the Portuguese traders, with their near exclusive access to the Chinese market, who became the most successful intermediaries of the Japan–China trade for the rest of the 16th century.

The Battles of Kawanakajima were a series of battles fought in the Sengoku period of Japan between Takeda Shingen of Kai Province and Uesugi Kenshin of Echigo Province from 1553 to 1564. Shingen and Kenshin contested each other for control of the plain of Kawanakajima between the Sai River and Chikuma River in northern Shinano Province, located in the present-day city of Nagano. The battles were triggered after Shingen conquered Shinano, expelling Ogasawara Nagatoki and Murakami Yoshikiyo, who subsequently turned to Kenshin for help. Five major battles of Kawanakajima occurred: Fuse in 1553, Saigawa in 1555, Uenohara in 1557, Hachimanbara in 1561, and Shiozaki in 1564. The most famous and severe battle was fought on 18 October 1561 in the heart of the Kawanakajima plain, thus being known the Battle of Kawanakajima. The battles were ultimately inconclusive and neither Shingen or Kenshin established their control over the plain of Kawanakajima.

The Battles of Kawanakajima became one of "the most cherished tales in Japanese military history", the epitome of Japanese chivalry and romance, mentioned in epic literature, woodblock printing, and movies.

The Imagawa, Hojo, and Takeda clans met at the Zentoku-ji temple in Suruga province and established a peace treaty. The proceedings were moderated by a monk named Taigen Sessai. The three daimyo agreed not to attack each other, as well as made agreements on support and reinforcements if necessary. This agreement was held together by three marriages - Hojo Ujimasa married the daughter of Takeda Shingen (Obai-in), Imagawa Ujizane married a daughter of Hojo Ujiyasu, and Takeda Yoshinobu had already married the daughter of Imagawa Yoshimoto in 1552, further strengthening ties between the Takeda and the Imagawa. Due to these agreements, the three daimyo were able to focus on their own goals without fear of attack.

The 1555 Battle of Miyajima was the only battle to be fought on the sacred island of Miyajima; the entire island is considered to be a Shinto shrine, and no birth or death is allowed on the island. Extensive purification rituals took place after the battle, to cleanse the shrine and the island of the pollution of death. The Battle of Miyajima was the turning point in a campaign for control of the Ōuchi clan and of Aki Province, a strategically important province for establishing control of western Honshu. It was an important step for the Mōri clan in taking the foremost position in western Japan, and cemented the reputation of Mōri Motonari as a cunning strategist.

In this battle, the heavily outnumbered Oda clan troops commandeered by Oda Nobunaga defeated Imagawa Yoshimoto and established himself as one of the front-running warlords in the Sengoku period. The Battle of Okehazama is regarded as one of the most significant turning points in Japanese history. The Imagawa clan was greatly weakened and would soon be destroyed by its neighbors. Oda Nobunaga gained greatly in prestige, and many samurai and minor warlords (including Imagawa's former retainer, Matsudaira Motoyasu, the future Tokugawa Ieyasu) pledged fealty.

In 1565, Matsunaga Danjo Hisahide's son Matsunaga Hisamichi and Miyoshi Yoshitsugu laid siege against a collection of buildings where Yoshiteru lived. With no help arriving in time from the daimyōs that could have supported him, Yoshiteru is killed in this incident. Three years passed before his cousin Ashikaga Yoshihide became the fourteenth shōgun.

On November 9, 1568, Nobunaga entered Kyoto, drove out the Miyoshi clan, who had supported the 14th shogun and who fled to Settsu, and installed Yoshiaki as the 15th shogun of the Ashikaga Shogunate. However, Nobunaga refused the title of shogun's deputy (Kanrei), or any appointment from Yoshiaki, even though Nobunaga had great respect for the Emperor Ōgimachi.

The Ishiyama Hongan-ji War, taking place from 1570 to 1580 in Sengoku period Japan, was a ten-year campaign by lord Oda Nobunaga against a network of fortifications, temples, and communities belonging to the Ikkō-ikki, a powerful faction of Jōdo Shinshū Buddhist monks and peasants opposed to the rule of the samurai class. It centered on attempts to take down the Ikki's central base, the cathedral fortress of Ishiyama Hongan-ji, in what is today the city of Osaka. While Nobunaga and his allies led attacks on Ikki communities and fortifications in the nearby provinces, weakening the Hongan-ji's support structure, elements of his army remained camped outside the Hongan-ji, blocking supplies to the fortress and serving as scouts.

In 1573, While still lord of the Hata district of Tosa, Ichijō Kanesada was unpopular and had already suffered the defection of a number of important retainers. Seizing the opportunity, Motochika wasted no time in marching on the Ichijō's headquarters at Nakamura, and Kanesada fled to Bungo, defeated. In 1575, at the Battle of Shimantogawa (Battle of Watarigawa), he defeated the Ichijo family. Thus he ended up gaining control of Tosa Province.

Following his conquest of Tosa, Motochika turned north and prepared for an invasion of Iyo province. The lord of that province was Kōno Michinao, a daimyo who had once been driven from his domain by the Utsunomiya clan, returning only with the assistance of the powerful Mōri clan. However, it was unlikely that Kōno could count on that sort of help again as the Mōri were embroiled in a war with Oda Nobunaga. Nonetheless, Chōsokabe's campaign in Iyo did not go off without a hitch.

In 1579, 7,000-man Chōsokabe army, commanded by Kumu Yorinobu, met the forces of Doi Kiyonaga at the Battle of Mimaomote. In the ensuing battle, Kumu was killed and his army defeated, though the loss proved little more than an unfortunate delay. The next year, Motochika led some 30,000 men into Iyo Province, and forced Kōno to flee to Bungo province.

With little interference from either the Mōri or the Ōtomo, Chōsokabe was free to press onwards, and in 1582, he stepped up ongoing raids into Awa province and defeated Sogō Masayasu and the Miyoshi clan at the Battle of Nakatomigawa.

Later, Motochika advanced to Sanuki province defeated Sengoku Hidehisa at Battle of Hiketa. By 1583, Chōsokabe forces had subdued both Awa and Sanuki. Over the ensuing decade, he extended his power to all of Shikoku island, making Motochika's dream of ruling all of Shikoku a reality.

Takeda Katsuyori became the daimyō of the Takeda clan. Katsuyori was ambitious and desired to continue the legacy of his father. He moved on to take Tokugawa forts. However an allied force of Tokugawa Ieyasu and Oda Nobunaga dealt a crushing blow to the Takeda in the Battle of Nagashino. Katsuyori committed suicide after the battle, and the Takeda clan never recovered.

Takeda Katsuyori attacked the castle when Okudaira Sadamasa rejoined the Tokugawa, and when his original plot with Oga Yashiro for taking Okazaki Castle, the capital of Mikawa, was discovered. Nobunaga's skillful use of firearms to defeat Takeda's cavalry tactics is often cited as a turning point in Japanese warfare; many cite it as the first "modern" Japanese battle.

The Battle of Tedorigawa took place near the Tedori River in Japan's Kaga Province in 1577, between the forces of Oda Nobunaga against Uesugi Kenshin. Kenshin tricked Nobunaga into launching a frontal attack across the Tedorigawa and defeated him. Having suffered the loss of 1,000 men, the Oda withdrew south. This was destined to be Kenshin's last great battle.

The Mori clan lost their strategic castle at Miki. By then, the siege was beginning to swing in Nobunaga's favor. The majority of the Ikki's allies were already inside the fortress with them, so they had no one to call on for aid. The Ikki under the leadership of Shimozuma Nakayuki, eventually the defenders were nearly out of ammunition and food, the Abbot Kōsa held a conference with his colleagues after receiving a letter of Advice via Imperial Messenger in April. Kōsa's son surrendered a few weeks later. The fighting finally ended in August 1580. Nobunaga spared the lives of many of the defenders, including Shimozuma Nakayuki, but burned the fortress to the ground. Three years later, Toyotomi Hideyoshi would begin construction on the same site, building Osaka Castle, a replica of which was constructed in the 20th century.

The Honnō-ji Incident was the assassination of Oda Nobunaga at the Honnō-ji temple in Kyoto on 21 June 1582. Nobunaga was betrayed by his general Akechi Mitsuhide during his campaign to consolidate centralized power in Japan under his authority. Mitsuhide ambushed the unprotected Nobunaga at Honnō-ji and his eldest son Oda Nobutada at Nijō Palace which resulted in both committing seppuku.

The Tenshō-Jingo conflict is a collection of battles and posturing between the Hōjō, Uesugi, and Tokugawa after the death of Oda Nobunaga. The campaign began with the Hōjō driving out the demoralized Oda forces under Takigawa Kazumasu. The Hōjō managed to capture Komoro castle, placing it under Daidoji Masashige. They pushed further into Kai, capturing and rebuilding Misaka Castle as they squared off against Ieyasu, who had made inroads by absorbing former Takeda officers into his army. Takigawa Kazumasu lost decisively against the invading Hōjō army at the Battle of Kannagawa and on July 9th, Masayuki defected to Hōjō's side. Meanwhile, Uesugi forces were invading northern Shinano. Both armies came to face each other at Kawanakajima on July 12th, but direct combat was avoided as the Hōjō army turned back and advanced south towards Kai province, which was in turn invaded by Tokugawa forces. At one point, the Hōjō clan had come close to controlling most of Shinano province, but Masayuki helped Yoda Nobushige, a local lord who had been resisting against Hōjō's advances in Shinano and was in touch with Tokugawa Ieyasu. He then defected to the Tokugawa's side on September 25. Faced with this sudden betrayal, Hōjō Ujinao saw his position in the conflict weaken and decided for a peace treaty and alliance with the Tokugawa clan, which was agreed upon on October 29th. This event marked the end of the conflict which lasted for roughly 5 months after Nobunaga's death.

In the Honnō-ji Incident, Akechi Mitsuhide, a retainer of Oda Nobunaga, attacked Nobunaga as he rested in Honnō-ji, and forced him to commit seppuku. Mitsuhide then took over Nobunaga's power and authority around the Kyoto area. Thirteen days later, Oda's forces under Toyotomi Hideyoshi met Mitsuhide at Yamazaki and defeated him, avenging his lord (Nobunaga) and taking Nobunaga's authority and power for himself.

Working together with his brothers Yoshihiro, Toshihisa, and Iehisa, he launched a campaign to unify Kyūshū. Starting in 1572 with a victory against Itō clan at the battle of Kizaki and the Siege of Takabaru in 1576, Yoshihisa continued to win battles. In 1578, he defeated the Ōtomo clan at the battle of Mimigawa, though he did not take their territory. Later, in 1581, Yoshihisa took Minamata castle with a force of 115,000 men. In early 1584, he was victorious in Battle of Okitanawate against Ryūzōji clan and defeated the Aso clan.

By the middle of 1584, the Shimazu clan controlled; Chikugo, Chikuzen, Hizen, Higo, Hyūga, Osumi, and Satsuma, most of Kyūshū with the exception of Ōtomo's domain and unification was a feasible goal.

Like Nobunaga before him, Hideyoshi never achieved the title of shōgun. Instead, he arranged to have himself adopted by Konoe Sakihisa, one of the noblest men belonging to the Fujiwara clan and secured a succession of high court titles Chancellor (Daijō-daijin), including, in 1585, the prestigious position of Imperial Regent (kampaku). In 1586, Hideyoshi was formally given the new clan name Toyotomi (instead of Fujiwara) by the Imperial court.

In June, 1585, Hideyoshi amassed a giant army of 113,000 men to invade Shikoku and divided them into three forces. The first, under his half-brother Hashiba Hidenaga and nephew Hashiba Hidetsugu, consisted of 60,000 men, and assaulted the provinces of Awa and Tosa, approaching Shikoku via Akashi island.

The third force was led by Mōri "Two Rivers", Kobayakawa Takakage and Kikkawa Motoharu, consisted of 30,000 men, and advanced on the province of Iyo. In total, it took 600 larger ships and 103 smaller ships to transport Hideyoshi's army across the Seto Inland Sea to Shikoku.

By August, Hideyoshi's invasion culminated in the siege of Ichinomiya Castle, with around 40,000 men under Hidenaga besieging the castle for 26 days. Hidenaga managed to destroy the water source of Ichinomiya Castle, Chōsokabe half-heartedly tried to relief the castle from siege, Ichinomiya finally surrendered. With the surrender of the castle, Chosokabe Motochika himself surrendered

The Kyūshū campaign of 1586–1587 was part of the campaigns of Toyotomi Hideyoshi who sought to dominate Japan at the end of the Sengoku period. Having subjugated much of Honshū and Shikoku, Hideyoshi turned his attention to the southernmost of the main Japanese islands, Kyūshū, in 1587.

In 1588, Toyotomi Hideyoshi, having become kampaku or "imperial regent", ordered a new sword hunt; Hideyoshi, like Nobunaga, sought to solidify separations in the class structure, denying commoners weapons while allowing them to the nobility, the samurai class. In addition, Toyotomi's sword hunt, like Nobunaga's, was intended to prevent peasant uprisings and to deny weapons to his adversaries. Toyotomi claimed that the confiscated weapons would be melted down and used to create a giant image of the Buddha for the Asuka-dera monastery in Nara.

Toyotomi Hideyoshi defeats the Hōjō clan, unifying Japan under his rule. The third siege of Odawara was the primary action in Toyotomi Hideyoshi's campaign to eliminate the Hōjō clan as a threat to his power. Tokugawa Ieyasu, one of Hideyoshi's top generals, was given the Hōjō lands. Though Hideyoshi could not have guessed it at the time, this would turn out to be a great stepping-stone towards Tokugawa's attempts at conquest and the office of Shōgun.

The invasions were launched by Toyotomi Hideyoshi with the intent of conquering the Korean Peninsula and China, which were respectively ruled by the Joseon and Ming dynasties. Japan quickly succeeded in occupying large portions of the Korean Peninsula, but the contribution of reinforcements by the Ming, as well as the disruption of Japanese supply fleets along the western and southern coasts by the Joseon navy, forced a withdrawal of Japanese forces from Pyongyang and the northern provinces to the south in Busan and nearby regions. Afterwards, with righteous armies (Joseon civilian militias) launching guerrilla warfare against the Japanese and supply difficulties hampering both sides, neither were able to mount a successful offensive or gain any additional territory, resulting in a military stalemate. The first phase of the invasion lasted from 1592 until 1596, and was followed by ultimately unsuccessful peace negotiations between Japan and the Ming between 1596 and 1597.

Without leaving a capable successor, the country was once again thrust into political turmoil, and Tokugawa Ieyasu took advantage of the opportunity. On his deathbed, Toyotomi appointed a group of the most powerful lords in Japan—Tokugawa, Maeda Toshiie, Ukita Hideie, Uesugi Kagekatsu, and Mōri Terumoto—to govern as the Council of Five Regents until his infant son, Hideyori, came of age. An uneasy peace lasted until the death of Maeda in 1599. Thereafter a number of high-ranking figures, notably Ishida Mitsunari, accused Tokugawa of disloyalty to the Toyotomi regime. This precipitated a crisis that led to the Battle of Sekigahara.

The Battle of Sekigahara was a decisive battle on October 21, 1600 at the end of the Sengoku period. This battle was fought by the forces of Tokugawa Ieyasu against a coalition of Toyotomi loyalist clans under Ishida Mitsunari, several of which defected before or during the battle, leading to a Tokugawa victory. The Battle of Sekigahara was the largest battle of Japanese feudal history and is often regarded as the most important. Toyotomi's defeat led to the establishment of the Tokugawa shogunate.

Tokugawa Ieyasu took three more years to consolidate his position of power over the Toyotomi clan and the various daimyō, but the Battle of Sekigahara is widely considered to be the unofficial beginning of the Tokugawa shogunate.

The Tokugawa shogunate was established by Tokugawa Ieyasu after victory at the Battle of Sekigahara, ending the civil wars of the Sengoku period following the collapse of the Ashikaga shogunate. Ieyasu became the shōgun, and the Tokugawa clan governed Japan from Edo Castle in the eastern city of Edo (Tokyo) along with the daimyō lords of the samurai class. This period if Japanese history is known as the Edo period.

The Tokugawa shogunate organized Japanese society under the strict Tokugawa class system and banned most foreigners under the isolationist policies of Sakoku to promote political stability. The Tokugawa shoguns governed Japan in a feudal system, with each daimyō administering a han (feudal domain), although the country was still nominally organized as imperial provinces. Under the Tokugawa shogunate, Japan experienced rapid economic growth and urbanization, which led to the rise of the merchant class and Ukiyo culture.

The period culminated with a series of three warlords – Oda Nobunaga, Toyotomi Hideyoshi, and Tokugawa Ieyasu – who gradually unified Japan. After Tokugawa Ieyasu's final victory at the siege of Osaka in 1615, Japan settled down into over 200 years of peace under the Tokugawa shogunate.