As Yoshinobu TOKUGAWA and Yoshinaga MATSUDAIRA, who had been forced to retire from the forefront of politics since Ansei no Taigoku, returned to the political scene, the reform of the bakufu was expected to be promoted, but eventually the difference of the opinion with Hisamitsu SHIMAZU surfaced and led to the confrontation.
安政の大獄以来、逼塞に追い込まれていた徳川慶喜・松平慶永らが表舞台に復帰したことにより幕府の改革は進むかに見えたが、やがて島津久光との意見の相違が明らかとなり、対立することとなる。