Aritomo Yamagata was a Japanese general and a member of the oligarchy which dominated Meiji Japan. He was instrumental in building a modern army, strengthening the power of the civil and military bureaucracy, and checking the development of popular influences on the government.

Aritomo Yamagata was born the son of a low-ranking samurai family on April 22, 1838, in Hagi, the castle town of Choshu domain. Like Hirobumi Ito Yamagata studied at the private academy of Shoin Yoshida, who advocated revolt against unworthy rulers and severely criticized the shogunate's weak response to the Western nations. Not surprisingly, Yamagata became an active participant in the imperial loyalist movement in Choshu. As an officer of the Kiheitai, a militia force made up of both peasants and samurai, he fought under the leadership of Shinsaku Takasagi in engagements with the Westerners at shimonoseki, in the Choshu civil war, and in the wars of the restoration.

During the 1870s Yamagata became the main force behind the organization of a national army. He was the chief architect of the military conscription law of 1873, which created an army recruited from the peasantry and other commoners as well as from the former samurai class. He also introduced in 1879 the German model of a general-staff system of military administration, which made the army independent of civilian control. He held high-ranking positions in the army until his death, exercising considerable influence on military planning and policy, and his proteges dominated the military high command down to the early 1920s.

Although Yamagata was radical in his military innovations, he was a thoroughgoing conservative in civilian politics. As minister of home affairs from 1883 to 1888, he built up a strong centrally controlled police force, drafted laws suppressing political opposition, and reorganized the local government system in order to strengthen the power of local officials to maintain local order