After the First Sino-Japanese War and the Russo-Japanese War, Korea was ruled by Japan from 1910 to 1945. Korean resistance groups known as Dongnipgun (Liberation Army) operated along the Sino-Korean border, fighting guerrilla warfare against Japanese forces. Some of them took part in allied action in China and parts of South East Asia. One of the guerrilla leaders was the communist Kim Il-sung, who later became the first leader of North Korea.