In 1556, Yamabuki Castle, which supported the Ouchi clan, was assailed by a host of 25,000 men led by Haruhisa AMAGO who had quickly withdrew his forces from Bizen and by Nagataka OGASAWARA who had joined forces with Amago.
弘治2年（1556年）、備前遠征から素早く兵を撤兵させた尼子晴久率いる25000と、尼子と手を結んだ小笠原長雄が大内方であった山吹城を攻撃。