In 1868, while marching his troops as the counselor of Tosando-Road spearhead government-general of the new government, he changed his family name back to Itagaki, the one his ancestors had proclaimed, as February 14, the day they arrived in Ogaki in Mino Province just before seizing Kofu Castle in a shogunal demesne, coincidently marked the 320th anniversary of the death of Nobukata ITAGAKI.
慶応4年（1868年）新政府東山道先鋒総督府参謀として進軍していた退助は、天領（旧幕府領）の甲府城に掌握を目前に、美濃国大垣に着いた2月14日が、板垣信方の没後320年にあたるため、先祖の旧姓とする板垣姓に改姓した。