Conflict between the lords of the Tamarinoma (including Naosuke), Masahiro ABE, and Nariaki TOKUGAWA came to a head with a discussion in the Saiko no Ma (West Lake Room) of Edo-jo Castle regarding the conclusion of the treaty between the United States of America and the Empire of Japan.
直弼ら溜間詰諸侯と、阿部正弘・徳川斉昭の対立は、日米和親条約の締結をめぐる江戸城西湖の間での討議で頂点に達した。