In September 1933 Chiang Kai-shek assembled some 500,000 troops and launched the fifth "encirclement and suppression" campaign against the Central Revolutionary Base Area by the new strategy of using blockhouses. At the time the Communist Party leadership, influenced by Wang Ming's "Left" adventurism, erroneously practiced positional warfare instead of guerrilla and mobile warfare. They were adventuristic when on the offensive, then made mistakes of being conservative when on the defensive. As a result, the Red Army lost many battles, became unable to take effective action and failed to break the "encirclement and suppression" campaign after a year of bitter fighting. In October 1934 the main force of the Central Red Army was forced to withdraw from the Central Revolutionary Base Area and began the Long March.