Weakened by the punitive attack by the Western powers, Chōshū was unable to withstand the expedition mounted by the "Bakufu" in autumn 1864 in retaliation for previous Chōshū attempts to seize control of Kyoto. At first, conservative forces, which favored conciliation with the "Bakufu" in order to secure the domain, were dominant in Chōshū politics, and Takasugi and some of his compatriots had to leave the domain to avoid renewed imprisonment. Takasugi, with only about a dozen followers, including future political leaders Yamagata Aritomo, Itō Hirobumi and Inoue Kaoru, gathered in Kokura in Kyūshū and prepared an attack on the conservative forces in Chōshū. The subsequent Chōshū civil war began on 13 January 1865.