In 1578, Terumoto MORI, a sosui (commander-in-chief) of the Mori family, mobilized a large force of more than hundred thousand soldiers to regain control of Kozuki-jo Castle in Harima Province, basing the headquarters of his army in Bichu at Takamatsu-jo Castle, where he deployed Motoharu KIKKAWA, Takakage KOBAYAKAWA, Tadaie UKITA and 61,000 sailors from the Murakami navy in Harima in the Siege of Kozuki-jo Castle.
天正6年（1578年）、播磨国上月城を奪還すべく毛利家の総帥・毛利輝元が10万以上の大軍を動員し、自らは備中高松城に本陣を置き、吉川元春、小早川隆景、宇喜多忠家、村上水軍の6万1,000人を播磨に展開させ上月城を包囲した。