It was Hideyoshi HASHIBA who defeated Mitsuhide in the Battle of Yamazaki, then crushed Katsuie SHIBATA in the Battle of Shizugatake, and thus secured his position as successor to Nobunaga.
山崎の戦いで光秀を討ち、続いて賤ヶ岳の戦いで柴田勝家を滅ぼして信長の後継者の地位を確実にしたのは羽柴秀吉であった。