Since Imperial Prince Oshikuma was afraid the child prince would ascend to the throne as the next Emperor when he knew the death of the Emperor Chuai and the birth of his baby prince (the Emperor Ojin), he conspired with Imperial Prince Kogasaka, his older brother, to attack the Empress army during their retuning trip from Tsukushi Province.
との報に接した忍熊皇子は、次の皇位が幼い皇子に決まることを恐れ、兄の坂皇子と共謀して、筑紫国から凱旋する皇后軍を迎撃しようとした。