The Ōnin War

The Ōnin War, lasting for 11 years from 1467, was an unprecedented conflict that reduced Kyoto to a burned wasteland. As a result, the Muromachi shogunate effectively collapsed, and Japan entered the Warring States period.

Basic Knowledge

The causes of the Ōnin War involved several overlapping conflicts.
① Succession dispute surrounding the eighth shogun, Ashikaga Yoshimasa: Yoshimasa had adopted his younger brother, Ashikaga Yoshimi, but his wife, Hino Tomiko, gave birth to their biological son, Ashikaga Yoshihisa, leading to a dispute over succession.
② Succession dispute within the Hatakeyama clan, a kanrei family: Hatakeyama Masanaga versus Hatakeyama Yoshinari.
③ Succession dispute within the Shiba clan, another kanrei family.
Against this background, the powerful provincial constables Hosokawa Katsumoto (Eastern Army) and Yamana Mochitoyo (Sōzen) (Western Army) came into conflict. In May 1467, full-scale fighting began in Kyoto (the Ōnin War).
The Eastern Army is said to have numbered 160,000 and the Western Army 110,000. Kyoto's urban area was burned and became a battlefield. Katsumoto and Sōzen died one after another in 1473, and the war finally ended in 1477. There was no victor; it became a quagmire in which even the purpose of the war was forgotten.
The conflict spread to the provinces, and provincial constables returned to their domains and strengthened their self-defense. Eventually, the Warring States period began, as provincial constables declined and their vassals seized control through gekokujō.

Further Study (Background and Influence)

Kyoto was completely destroyed in the Ōnin War. Many court nobles and temples fled to the provinces, producing the unintended effect of spreading Kyoto culture to the provinces. For example, the Ichijō clan of Tosa is a representative example of court nobles becoming provincial warlords. The renga poet Sōgi also traveled throughout the country and spread linked verse.
The authority of the shogunate completely declined. The ninth shogun, Ashikaga Yoshihisa, the tenth, Ashikaga Yoshitane, and the eleventh, Ashikaga Yoshizumi, succeeded one another in a short period, and the shogunate became a weak government ruling only the area around Kyoto.
In the provinces, deputy provincial constables and local warriors who held real power locally rose in place of the provincial constables who remained in Kyoto. The trend of gekokujō (those below overthrowing those above) spread, and Warring States daimyos emerged throughout Japan. The Ōnin War became a turning point from the medieval period to the early modern period.

Points of Caution (Easily Confused)

① Be sure to remember Eastern Army = Hosokawa and Western Army = Yamana. One mnemonic is “Hosokawa = east (right side), Yamana = west (left side).”
② Do not confuse Ashikaga Yoshimi (Yoshimasa's younger brother and adopted son) with Ashikaga Yoshihisa (Yoshimasa's biological son).
③ Hino Tomiko was the wife of eighth shogun Yoshimasa and provoked the great conflict by trying to make her biological son Yoshihisa shogun. She has been criticized as a woman in history, but has also been reevaluated in recent years.
④ The Ōnin War had no victor. The commanders of both armies died of illness, and the purposeless quagmire continued for 11 years.

Practice

1. Give the year in which the Ōnin War began and the year in which it ended.
2. Give the names of the commanders of the Eastern Army and the Western Army in the Ōnin War.
3. Give the name of the shogun during the Ōnin War and the name of his wife.