The Battle of Uji in 1180 marked the opening military clash of the Genpei War between the Minamoto and Taira clans.
The fighting began after Prince Mochihito issued a call for the Minamoto clan and other opponents to resist Taira control of the imperial government. Minamoto no Yorimasa supported the prince and tried to block Taira forces at the bridge over the Uji River, south of Kyoto.
Minamoto defenders removed bridge planks to slow the attackers. The Taira army nevertheless crossed the river and defeated the smaller force. Yorimasa fled to Byōdō-in, where he performed ritual suicide, while Mochihito was killed soon afterward.
The battle did not end the conflict; it began a five-year war that concluded with the Minamoto victory at Dan-no-ura in 1185. Uji is sometimes confused with the later 1184 Battle of Uji, fought during a separate phase of the same broader struggle.