This paper aims to study the relationship between the Choshu Clan and Britain under sending troops of the Tokugawa shogunate to the Choshu Clan, and focus on a point of view of Britain. In 1864, the Tokugawa shogunate ordered feudal lords to send their troops to the Choshu Clan. In 1866, the war between the Tokugawa forces and the Choshu clan finally broke out. British ministers to Japan communicated with some Choshu retainers several times during the two years. In this paper, the relationship between both sides is made an analysis from point of view of Britain, based on some British despatches and letters.