After his older brother Nariakira died, Hisamitsu SHIMAZU became Kokufu (father of the country) (also called "Lord of the Second Citadel") to assist his son Tadayoshi SHIMAZU, who became a new lord, and he carried out his older brother's last wish to move up to Kyoto with the troops, which his older brother could not accomplish, attempting to promote the bakufu's political reform by having the imperial court dispatch the envoy.
兄・斉彬の死後、藩主となった子の島津忠義を補佐する国父（副城公）の立場となった島津久光は、兄の遺志を継ぎ、兄の果たせなかった率兵上京を敢行し、朝廷から勅使を出させることで幕政の改革を推し進めようと図った。