Among others, an incident in which the imperial court sent an imperial order directly to the Mito clan (Boshin no Micchoku) made Ii and the cabinet officials of the shogunate stay alert, and they clamped down on the Mito clan severely.
特に幕府・関白を介さず、朝廷から直接水戸藩へ勅書が出された件（戊午の密勅参照）は井伊ら幕閣の警戒感を強め、水戸藩への弾圧は苛烈を極めた。