Prince Yamagata Aritomo was a Japanese statesman and general who twice served as prime minister of Japan, in 1889–1891 and 1898–1900. He was a leading member of the genrō, a group of senior courtiers and statesmen who dominated the politics of Japan during the Meiji era. As the Imperial Japanese Army's inaugural Chief of Staff, he was the chief architect of its nationalist and reactionary ideology, which has led some historians to consider him the "father" of Japanese militarism.