In previous decades, PRC propaganda was crucial to the formation and promotion of the cult of personality centered around Chairman Mao Zedong. It also served as a useful tool for mobilizing popular participation in national campaigns such as the 1958 Great Leap Forward and the 1966-76 Cultural Revolution. Following the death of Mao in 1976, propaganda was used to blacken the character of the notorious Gang of Four, which was seen as responsible for the excesses of the Cultural Revolution. Past propaganda also encouraged the Chinese people to emulate selfless model workers and soldiers such as the famous Comrade Lei Feng, suicidal Chinese Civil War hero Dong Cunrui, self-sacrificing Korean War hero Yang Gensi, and Dr. Norman Bethune, a Canadian doctor who assisted the Communist Eighth Route Army during the Second Sino-Japanese War. It also praised Third World revolutionaries and close foreign allies such as Albania and North Korea while vilifying both the United States “imperialists” and the Soviet “revisionists” (the latter of whom was seen as having betrayed Marxism-Leninism).