5Imperialism, the Highest Stage of Capitalism (1917), by Vladimir Lenin, describes the function of financial capital in generating profits from imperialist colonialism as the final stage of capitalist development to ensure greater profits. The essay is a synthesis of Lenin's modifications and developments of economic theories that Karl Marx formulated in Das Kapital (1867). In his Prefaces, Lenin states that the First World War (1914-1918) was "an annexationist, predatory, plunderous war" among empires, whose historical and economic background must be studied "to understand and appraise modern war and modern politics".