The Battle of Koromo River took place during the opening years of the Kamakura period (12th century) of Japan.

Hidehira appointed Yoshitsune as general to be opposed to Yoritomo, but he died of illness on October 29, 1187.

Yoritomo strongly pressured Fujiwara no Yasuhira, the 2nd son and successor of Hidehira, through the Imperial Court to arrest Yoshitsune.

On June 15, 1189,[2] he led 500 soldiers to attack Yoshitsune and an entourage of servants in the Koromogawa no tachi residence.

Benkei supposedly died standing up, which caused great fear in his enemies.