THE SPLIT INTO TWO PARTIES  
As a result of increasing differences, a final split between the two factions occurred in 1912. Thereafter the two parties, together with others, competed for the leadership of the antitsarist revolution. The Bolsheviks used both legal and underground tactics to advance their programme, building a membership, in accordance with Lenin's original specifications, of about 45,000 by March 1917, and 240,000 by July of that year. The Bolsheviks opposed World War I as an imperialist conflict in which socialists should have no part, but the Mensheviks and Social Revolutionaries, placing national before class interests, supported and eventually attempted to take leadership in the Russian war effort. As a result of the collapse of the Russian armies and the growing awareness of the inefficiency of the government, a revolution broke out in March 1917, resulting in the abdication of the tsar and the introduction of parliamentary government. The provisional government, which included Mensheviks, was charged by the Bolsheviks with an unwillingness to expand the revolution in the direction of socialism. The Bolsheviks undertook this task through the soviets of workers and soldiers. The Bolsheviks seized state power in November 1917. In 1918, under the new name of the Communist (Bolshevik) party adopted from an earlier organization led by Marx, they began their career as the dominant, and later, by decree, the sole political organization in the USSR. The subsequent history of the theory and practice of Bolshevism is indistinguishable from that of Soviet Communism.