The 1467–1477 conflict that severely weakened the Ashikaga shogunate was the Ōnin War.
The war began in Kyoto during a succession dispute involving the Ashikaga shogun’s heir and rival powerful families. The Hosokawa and Yamana clans supported opposing sides, and fighting devastated much of the capital. Although the conflict formally ended in 1477, it did not restore strong central authority.
The Ōnin War is often treated as the opening of the Sengoku period, an era of intense political fragmentation and warfare among competing daimyō. Regional lords expanded their power, built castles, and relied on large armies of samurai and ashigaru.
The conflict was not a single decisive battle. It became a prolonged struggle marked by shifting alliances and destruction in Kyoto. The Ashikaga shogunate survived nominally for decades, but its ability to control Japan was greatly reduced.