The Samurai Warrior in History
The Muromachi Period:
The regional constabulary in Japan, known as the "daimyo", continued to gain power in the 1400s, and by 1460, were not obeying orders from the shogun, besides backing different successors to the imperial throne. In 1464, when the Shogun Ashikaga Yoshimasa resigned, a bitter dispute raged between the backers of Yoshimasa’s younger brother and his son, which set alight even more bickering amongst the daimyo.
This in-fighting erupted into the decade-long Onin War in 1467. Many thousands died in this war, and Kyoto was burned to the ground.
As a direct result of the Onin War, Japan’s warring states period, or Sengoku, began; and various daimyo fought for national dominance throughout almost all of Japan’s provinces.
This period was ending in 1568, when the Japanese warlord Oda Nobunaga defeated three other powerful daimyo in battle. This warlord then marched into and claimed Kyoto, and installed his favorite, Nobunaga, as Shogun. This new Shogun spent the much of the next 14 years quelling rival daimyo, and quashing rebellions by Buddhist monks.
Nobunaga was assassinated by one of his generals in 1582. Another general, Hideyoshi, completed the unification of Japan and ruled as regent. Hideyoshi went on to invade Korea in 1592 and again in 1597.