Japanese Wars of Unification Summary

  • Last updated on November 11, 2022

After nearly a century of civil war and decentralization of authority in Japan, three successive generals—Oda Nobunaga, Toyotomi Hideyoshi, and Tokugawa Ieyasu—defeated rival warlords and formed the basis of a new system of social and political order that lasted until the nineteenth century.

Summary of Event

From the end of theŌnin War of 1467-1477 until the mid-sixteenth century, Japan was in the midst of what has come to be known as the Sengoku Jidai or Warring Warring States period (Japan, 1477-1600) States period. The feudal order of the Ashikaga shoguns had been replaced by a state of constant warfare as local strongmen known as sengoku daimyō vied with one another for territorial control. By the 1550’, a number of these regional warlords had increased their power to the point where they began to aim for national hegemony. Oda Nobunaga, the ruler of the province of Owari (near modern Nagoya in southern Honshū’s Aichi Prefecture), displayed a military genius and ruthlessness that made him stand out from his peers as the leading candidate in the drive toward national reunification. Japanese Wars of Unification (1550-1593) Oda Nobunaga Toyotomi Hideyoshi Tokugawa Ieyasu Akechi Mitsuhide Oda Nobunaga Oda Hikogoro Imagawa Yoshimoto Tokugawa Ieyasu Toyotomi Hideyoshi Asai Nagamasa Asakura Yoshikage Takeda Shingen Takeda Katsuyori Akechi Mitsuhide

Oda Nobunaga inherited control of part of Owari Province on the death of his father in 1551. After first consolidating his control over his father’s holdings, Nobunaga in 1555 moved against Hikogoro, a member of another branch of the Oda family in Owari. Nobunaga defeated Hikogoro in battle and continued his campaign, eventually bringing all of Owari under his sway by 1560.

The actions of the ambitious young general in Owari attracted the attention of Imagawa Yoshimoto of neighboring Mikawa. Imagawa sought to attack Nobunaga before the upstart could expand his power further and led a force of twenty-five thousand troops into Owari in June of 1560. Contemporary accounts report that Nobunaga could raise a force of only three thousand to defend his territory. However, on June 12, Nobunaga seized an opportune moment during a fierce storm to take Imagawa unawares and soundly routed the larger army. Imagawa was killed during the panic, and Nobunaga found himself in a strong strategic position on the south coast of the main Japanese island.

In 1561, one of the important Imagawa vassals, Matsudaira Takechiyo, who shortly thereafter changed his name to Tokugawa Ieyasu, allied himself with Nobunaga. Around the same time, a young officer in Nobunaga’s service named Kinoshita Hideyoshi (better known by his later name Toyotomi Hideyoshi) was beginning to distinguish himself.

By the late 1560’, Nobunaga had subjugated other territories around Owari. By 1568, Nobunaga’s power in central Japan was secured to the point where he was able to march into Kyōto and install a candidate of his choice into the office of shogun. The position had long since been reduced to a figurehead, but Nobunaga rightly concluded that control over the shogunate would be useful in giving his campaign of expansion more legitimacy.

In 1570, Nobunaga and his ally Tokugawa Ieyasu challenged the powerful warlords Asai Nagamasa and Asakura Yoshikage to the north of Kyōto. After a number of initial setbacks, Nobunaga defeated their combined forces in the Battle of Anegawa Anegawa, Battle of (1570) . The victory was only temporary, however, and Nobunaga’s situation became increasingly grim as he also found himself pitted against an uprising of Pure Land Buddhist Jōdo Shinshū[Jodo Shinshu] followers known as the Ikkō Ikki Ikkō Ikki[Ikko Ikki] as well as the forces of Takeda Shingen, a powerful Eastern daimyo Daimyos who had allied himself with Asai and Asakura.

Partly through his own ingenuity and partly because of help from his generals, Toyotomi Hideyoshi and Tokugawa Ieyasu, Nobunaga gradually began to gain the upper hand. After being defeated by Shingen at the Battle of Mikatagahara Mikatagahara, Battle of (1573) in 1573, Nobunaga rallied and in 1573 eliminated both Asai and Asakura. In the following year, after a series of brutal attacks, Nobunaga broke the Ikkō Ikki fortress of Nagashima, and the movement’s vitality was sapped. In 1575, he employed firearms to great effect with a victory over Takeda Shingen’s son Katsuyori in the Battle of Nagashino Nagashino, Battle of (1575) .

In 1576, Nobunaga relocated his headquarters to Azuchi Castle to the north of Kyōto and began to concentrate his military efforts against the Mōri Mōri family[Mori family] , a powerful family in Western Japan. Hideyoshi proved to be a key figure in this fight, and by 1580 the Mōri had been significantly weakened. In 1580, Nobunaga also secured the surrender of theŌsaka Honganji, the last powerful stronghold of Pure Land Buddhism, and effectively eliminated it as a military player.

In 1582, however, Nobunaga was betrayed by Akechi Mitsuhide, one of his generals who was preparing to lead an expedition against the Mōri. Nobunaga killed himself at Honnoji, a Buddhist temple in Kyōto, to avoid capture, and the balance of power in Japan was inexorably altered. Hideyoshi quickly established himself as Nobunaga’s chief successor by eliminating Akechi at the Battle of Yamazaki Yamazaki, Battle of (1582) .

Hideyoshi initially found himself in conflict with Tokugawa Ieyasu, but the two quickly realized that an alliance was more beneficial. Ieyasu continued to consolidate his holdings in the east, while Hideyoshi, after having gained the court title of kampaku (imperial regent) in 1585, began to concentrate his efforts on subduing the southern Japanese island of Kyūshū. In 1588, Hideyoshi used the prestige of his new court title to secure the allegiance of all of the daimyo in central Japan. In that year, he also promulgated his famous “sword hunt” edict, which helped to preserve order by disarming the peasant class. He and Ieyasu then combined their forces to war against the Hōjō family Hōjō family, later[Hojo family, later] in the Kantō region of the east and eventually laid siege to their fortress at Odawara, which was surrendered in 1590. Hideyoshi granted Ieyasu lordship over the Kantō region after the fighting had ended.

With the victory over Odawara, Hideyoshi had come to exercise a military power almost unprecedented in Japanese history. In 1592, he chose to direct this power abroad with an invasion of Korea Korea, Japanese invasion of . Because of long supply lines, disease, and fierce resistance in the Korean peninsula, the fighting there was a stalemate. In 1593, Chinese forces intervened and Hideyoshi’s representatives began peace negotiations. His authority in Japan, however, seemed unshakable, and after nearly fifty years of campaigns that had been begun by Oda Nobunaga, the Japanese wars of unification had effectively come to an end.


By 1593, Hideyoshi’s most productive and energetic years were behind him. Some scholars theorize that he may have suffered from mental illness between this time and his death in 1598. Tokugawa Ieyasu, who had prevented this dissipation of his military might by declining to participate in Hideyoshi’s Korean adventure emerged as Hideyoshi’s successor after defeating a coalition of rivals in the Battle of Sekigahara Sekigahara, Battle of (1600) in 1600. In 1603, Tokugawa Ieyasu was given the title of shogun by the emperor. This marks the beginning of the Tokugawa shogunate Tokugawa shogunate , which continued to rule Japan until the nineteenth century. The system of feudal alliances and territorial holdings that originated during the time of Nobunaga and Hideyoshi was further developed under Ieyasu and given a legal legitimacy that lasted as long as the rule of his successors.

Despite the destruction wrought during these wars of unification, the period between 1550 and 1593 was also a period of significant economic growth. As early as 1569, Nobunaga ordered the destruction of toll barriers to provide an impetus to the development of commerce. Nobunaga and Hideyoshi also aggressively pursued trade with Western powers such as Spain and Portugal, resulting in an increased role for Japan in the burgeoning global economy.

In addition, Nobunaga and Hideyoshi were both recognized as great patrons of the arts as well as great generals, and the period is considered something of a cultural renaissance in the history of Japan. New styles of art incorporating Western influences were perfected, and the quality of domestic craft in areas such as architecture continued to advance.

Further Reading
  • citation-type="booksimple"

    xlink:type="simple">Sansom, George. A History of Japan, 1334-1615. 3 vols. Stanford, Calif.: Stanford University Press, 1961. Despite its age, Sansom’s history of premodern Japan is still the most authoritative on the subject in English. Includes detailed coverage of the wars of unification.
  • citation-type="booksimple"

    xlink:type="simple">Sato, Hiroaki. Legends of the Samurai. New York: The Overlook Press, 1995. This work contains accounts of the careers of Nobunaga, Hideyoshi, and Ieyasu as well as details about their battles.
  • citation-type="booksimple"

    xlink:type="simple">Turnbull, Stephen. Samurai Warfare. London: Arms and Armour Press, 1996. The best English language history of the Japanese wars of unification.

1457-1480’s: Spread of Jōdo Shinshū Buddhism

1467-1477: Ōnin War

1477-1600: Japan’s “Age of the Country at War”

Mar. 5, 1488: Composition of the Renga Masterpiece Minase sangin hyakuin

Beginning 1513: Kanō School Flourishes

1532-1536: Temmon Hokke Rebellion

1549-1552: Father Xavier Introduces Christianity to Japan

1550’s-1567: Japanese Pirates Pillage the Chinese Coast

Sept., 1553: First Battle of Kawanakajima

June 12, 1560: Battle of Okehazama

1568: Oda Nobunaga Seizes Kyōto

1587: Toyotomi Hideyoshi Hosts a Ten-Day Tea Ceremony

1590: Odawara Campaign

1592-1599: Japan Invades Korea

1594-1595: Taikō Kenchi Survey

Oct., 1596-Feb., 1597: San Felipe Incident

Oct. 21, 1600: Battle of Sekigahara

Categories: History