A slogan introduced by Mao Zedong in 1940, noted again by Liu Shaoqi in 1958, and used more frequently in connection with leftist attacks on the "cultural front" in late 1965 and early 1966. The expression was used to denote the Great Proletarian Cultural Revolution, a political campaign officially inaugurated in August 1966 to rekindle revolutionary fervor of the masses outside formal party organizations. The Cultural Revolution decade (1966-76) can be divided into three periods: 1966-69, from the militant Red Guard (q. V. ) phase to the Ninth National Party Congress; 1969- 71, the period of the zenith and demise of Lin Biao; and 1971-76, the period of Mao's declining health and the ascendancy of the Gang of Four (q. V. ). At the August 1977 Eleventh National Party Congress, the Cultural Revolution was declared officially to have ended with the arrest in October 1976 of the Gang of Four.