Naosuke enforced the Ansei no Taigoku (a suppression of extremists by the Shogunate) to suppress the Hitotsubashi group (a group supporting Yoshinobu from the Hitotsubashi-Tokugawa family) and other opposition groups, but he was assassinated in the Sakuradamongai Incident.
一橋派や反対の弾圧である安政の大獄を行うが、桜田門外の変で暗殺された。