薩長同盟
After his return to Chōshū, Ōmura not only introduced modern western weaponry, but he also introduced the concept of military training for both "samurai" and commoners. The concept was highly controversial, but Ōmura was vindicated when his troops routed the all-samurai army of the Shogunate in the Second Chōshū Expedition of 1866. These same troops also formed the core of the armies of the Satchō Alliance at the Battle of Toba–Fushimi, Battle of Ueno and other battles of the Boshin War of the Meiji Restoration from 1867 to 1868.