After being banished from Kyoto by Nobunaga ODA, Yoshiaki ASHIKAGA who was the 15th Shogun of the Muromachi the Edo bakufu (Japanese feudal government headed by a shogun) moved his camp to Tomo, supported by the Mori and some other clans, where Yoshiaki attempted to seize the opportunity to defeat Nobunaga.
室町幕府15代将軍足利義昭は織田信長により京都を追放された後、毛利氏などの支援のもと鞆に拠点を移し信長打倒の機会を窺った。