In the Sakuradamongai Incident (1860), extremists murdered Tairo (a councilor of the Council of Five Elders) Naosuke II who had conducted Ansei no Taigoku (the suppression of extremists by the Shogunate), soon after that, in 1861 the Shogunate offered the lawful marriage of Seii Taishogun (literally, 'great general who subdues the barbarians') the 14th shogun Iemochi TOKUGAWA with Kazunomiya (a younger sister of Emperor Komei) to the Imperial Family for the purpose of gaining the Imperial Court's cooperation; especially since then, statesmen of strong clans including the Satsuma clan, the Choshu clan and the Tosa clan aimed for advance to the political center, and the following of Sonno Joi came to Kyoto one after and another.
特に安政の大獄を断行した大老井伊直弼が桜田門外の変で横死して後、公武合体を望む幕府が征夷大将軍徳川家茂の正室として孝明天皇の妹和宮の降嫁を求めた1861年（文久元年）頃から、薩摩藩・長州藩・土佐藩などの雄藩が中央政界への進出をうかがうようになり、尊王攘夷派がぞくぞくと京都に集まるようになった。