FACTIONAL DIFFERENCES  
The essential differences between the Bolsheviks and the Mensheviks appeared more clearly in subsequent years, when an apparent agreement on a Marxist programme—the overthrow of tsarism, the establishment of constitutional government, and, finally, the overthrow of capitalism and the establishment of a Communist society—resulted in wide variations in practice. The Bolsheviks supported the immediate objectives only insofar as they led in the direction of the final revolutionary aim. The Mensheviks, however, believing that Russia was not ready for revolution, placed the emphasis on reform, especially the establishment of constitutional government. Neither faction played a dominant role in the revolution that followed the defeat of Russia in the war with Japan in 1905. The workers' soviets (legislative bodies) were formed spontaneously, and Lenin failed at first to realize their importance. Leon Trotsky, who, as chairman of the St Petersburg Soviet, was the active leader of their revolution, was neither Bolshevik nor Menshevik, but stood between the two factions, striving to unite them. When, as a result of the revolution, a parliament, called the Duma, was established later in 1905, the Bolsheviks preferred at times to boycott it and at other times used it as a forum from which to agitate, whereas the Mensheviks hoped to build the strength of the antitsarists within it.