The Ōnin War , also known as the Upheaval of Ōnin and Ōnin-Bunmei war, was a civil war that lasted from 1467 to 1477, during the Muromachi period in Japan. Ōnin refers to the Japanese era during which the war started; the war ended during the Bunmei era. A dispute between a high official, Hosokawa Katsumoto, and a regional lord, Yamana Sōzen, escalated into a nationwide civil war involving the Ashikaga shogunate and a number of daimyō in many regions of Japan.

The Muromachi period or Muromachi era , also known as the Ashikaga period or Ashikaga era , is a division of Japanese history running from approximately 1336 to 1573. The period marks the governance of the Muromachi or Ashikaga shogunate, which was officially established in 1338 by the first Muromachi shōgun, Ashikaga Takauji, two years after the brief Kenmu Restoration (1333–1336) of imperial rule was brought to a close. The period ended in 1573 when the 15th and last shogun of this line, Ashikaga Yoshiaki, was driven out of the capital in Kyoto by Oda Nobunaga.