After the First Subjugation of Choshu that followed, he made every effort to secure the Emperor's permission on the Treaty of Amity and Commerce between the Unites States and Japan that had been left unauthorized by the Emperor; he succeeded in securing the Emperor's authorization albeit with provisos.
それに続く第一次長州征伐が終わると、無勅許状態にあった日米修好通商条約の勅許に奔走し、条件付ながら勅許を得ることに成功した。