Although the Ōuetsu Reppan Dōmei, comprising most of the domains of northern Japan, supported the Aizu han and Katamori, they were eventually defeated in the Aizu War. After a few years under house arrest in Tokyo, Katamori's life was spared, and he later became the Chief Priest of the Nikkō Tōshōgū Shrine. He died on December 5, 1893, and was buried by Shinto rites, receiving the posthumous Shinto name of Masane-reishin (忠誠雲神).