Katamori took his role as protector of Kyoto (and the Court) very seriously, and thus played a large role in the coup d'état of September 30 (or the coup d'état of August 18), and the Forbidden Gates Incident (禁門の変, Kinmon no Hen), which both involved clashes between the allied domainal forces under Shogunate command (including Aizu han) against the men of Chōshū han. During the Choshu Expeditions, he also advocated a hard line against the domain. These events lead to increased animosity towards Katamori and the Aizu han within the Chōshū han.