Ōnin was an era from 3/5 of 1467 to 4/28 of 1469 (based on the Japanese lunisolar calendar) at the beginning of the Sengoku period. The change in the name from the previous era (Bunshō) owed to war.
During this era:
Gotsuchi-Mikado served as the 103rd emperor of Japan from 1464 to 1500.
Ashikaga Yoshimasa served as the eighth shōgun of the Muromachi bakufu from the middle of the Muromachi period to the early Sengoku period (1449 to 1473). He succeeded Ashikaga Yoshikatsu, the seventh shōgun, who died at the age of nine, most likely from illness. Yoshimasa was the son of Ashikaga Yoshinori, the sixth shōgun, who died in a surprise attack while at an evening banquet, an event known as the Kakitsu Disturbance in 1441.
Date: 1/18 to 1/19 of Ōnin 1 (1467)
This conflict between the armies of Hatakeyama Yoshinari and Hatakeyama Masanaga was triggered by discord within the Hatakeyama clan which led to the Ōnin-Bunmei War, a multi-faceted conflict waged in Kyōto and the surrounding provinces that ran from 1467 to 1477.
Date: 5/26 to 5/27 of Ōnin 1 (1467)
Forces led by Yamana Mochitoyo of the Western Army clashed with forces under Hosokawa Katsumoto of the Eastern Army in the capital of Kyōto. This occurred in the beginning stages of the Ōnin-Bunmei War.
Date: Ōnin 1 (1467) to Bunmei 9 (1478)
This prolonged war arose from a succession conflict involving the Hatakeyama and Shiba clans who were serving a deputy shōgun of the Muromachi bakufu, and escalated into a power struggle between Hosokawa Katsumoto and Yamana Sōzen along with succession issues concerning Ashikaga Yoshimasa, the eighth shōgun of the Muromachi bakufu.
In 1468, Utsunomiya Shigetsuna: shugo daimyō, sengoku daimyō, seventeenth head of the Shimotsuke-Utsunomiya clan