Born in Hagi as the eldest son of Wada Masatake, a Choshu domain samurai, he trained at the Renpei-kan dojo in Edo under Saito Yakuro and became renowned as a master swordsman. Inspired by Yoshida Shoin, he joined the sonno joi movement. After the Kinmon Incident of 1864 he survived defeat and continued as the political leader of Choshu. Working with Saigo Takamori and Sakamoto Ryoma, he forged the Satcho Alliance of 1866, which proved decisive in overthrowing the shogunate. After the Meiji Restoration he became a pillar of the new government, spearheading the return of domains and the abolition of feudal domains to establish a centralized state. He joined the Iwakura Mission to observe Western institutions and argued for the need for constitutional government. He parted ways with Itagaki Taisuke and others who resigned over the Korea debate, taking a path of gradual reform. In his final years he was distressed by the outbreak of the Satsuma Rebellion and died at forty-four on May 26, 1877. Counted alongside Saigo and Okubo as one of the Three Great Meiji Reformers, he is highly regarded as a statesman and thinker indispensable to building the modern Japanese state.