Using the fact that the Choshu loyalists dared to fire their guns in the direction of the Imperial palace during the Hamaguri rebellion as a pretext, the Tokugawa shogunate labeled Choshu domain an official enemy of the Court, and as such launched the First Punitive Expedition against them.
禁門の変に於いて長州藩兵が御所へ向けて発砲した事等を理由に幕府は長州藩を朝敵として、第一次長州征伐を行う。