Had Iesada not done so, Naosuke II, the only fudai daimyo (a daimyo as a hereditary vassal to the Tokugawa family), would have been unable to punish his superiors, such as the Imperial Court and the Tokugawa family.
そうでもしなければ譜代大名に過ぎない井伊直弼が自分の目上に当たる朝廷・徳川一門を処罰することはできなかったのである。