The Taisei Hokan took place when the secret Imperial command to attack the shogunate was just about to be given to Satsuma Domain on the same day (it was supposed to reach Choshu Domain the next day), forestalling tobakuha (anti-Bakufu, crushing-the-Bakufu faction).
同じ13日、薩摩藩へ（翌日には長州藩へ）討幕の密勅が下される寸前に、倒幕派の機先を制した恰好となった。