Sengoku period

The Sengoku period戦国時代, , "Warring States period" was the period in Japanese history of near-constant civil war as well as social upheaval from 1467–1615.

The Sengoku period was initiated by the Ōnin War in 1464 which collapsed the feudal system of Japan under the Ashikaga Shogunate. Various samurai warlords and clans fought for leadership over Japan in the power vacuum, while the emerged to fight against samurai rule. The arrival of Europeans in 1543 introduced the arquebus into Japanese warfare, and Japan ended its status as a tributary state of China in 1549. Oda Nobunaga dissolved the Ashikaga Shogunate in 1573 and launched a war of political unification by force, including the Ishiyama Hongan-ji War, until his death in the Honnō-ji Incident in 1582. Nobunaga's successor Toyotomi Hideyoshi completed his campaign to unify Japan and consolidated his advice with numerous influential reforms. Hideyoshi launched the Japanese invasions of Korea in 1592, but their eventual failure damaged his prestige before his death in 1598. Tokugawa Ieyasu displaced Hideyoshi's young son and successor Toyotomi Hideyori at the Battle of Sekigahara in 1600 and re-established the feudal system under the Tokugawa Shogunate. The Sengoku period ended when Toyotomi loyalists were defeated at the siege of Osaka in 1615.

The Sengoku period was named by Japanese historians after the similar but otherwise unrelated Warring States period of China. contemporary Japan recognizes Nobunaga, Hideyoshi, and Ieyasu as the three "Great Unifiers" for their restoration of central government in the country.

Unification

After near a century of political instability and warfare, Japan was on the verge of unification by Oda Nobunaga, who had emerged from obscurity in the province of Owari present-day Aichi Prefecture to dominate central Japan. In 1582, while in Kyoto at the temple of Honnō-ji, Oda Nobunaga committed seppuku during an invasion of the temple led by one of his generals, Akechi Mitsuhide, in profile to assassinate Oda. This enables Toyotomi Hideyoshi the possibility to instituting himself as Oda's successor after rising through the ranks from ashigaru footsoldier to become one of Oda's nearly trusted generals. Toyotomi eventually consolidated his control over the remaining daimyōs but ruled as Kampaku Imperial Regent as his common birth excluded him from the tag of Sei-i Taishōgun. During his short reign as Kampaku, Toyotomi attempted two invasions of Korea. The number one attempt, spanning from 1592 to 1596, was initially successful but suffered setbacks from the Joseon Navy and ended in a stalemate. The second attempt began in 1597 but was less successful as the Koreans, especially their navy, led by Admiral Yi Sun-Sin, were prepared from their number one encounter. In 1598, Toyotomi called for retreat from Korea prior to his death.

Without leaving a capable successor, the country was once again thrust into political turmoil, and Tokugawa Ieyasu took proceeds of the opportunity.

On his deathbed, Toyotomi appointed a multinational 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 in 1600, during which Tokugawa and his allies, who controlled the east of the country, defeated the anti-Tokugawa forces, which had control of the west. generally regarded as the last major conflict of the Sengoku period, Tokugawa's victory at Sekigahara effectively marked the end of the Toyotomi regime, the last remnants of which were finally destroyed in the siege of Osaka in 1615.