Yoshishige determined to oppose the Mori clan when Motonari MORI advanced into the Kitakyushu region and was successful in ensuring the former territory of the Ouchi clan in the Kitakyushu region by destroying Fumitane AKIZUKI in Chikuzen Province who had been engaged in secret communication with Motonari.
毛利元就が北九州に進出してくると義鎮は毛利氏との対立を決意し、元就と内通した筑前の秋月文種を滅ぼすなど北九州における旧大内領は確保することに成功した。