Excerpt from Howard Zinn's A People's History of the United States: 1492 - Present (363-4):
A remarkably perceptive article on the nature of the First World War appeared in May 1915 in the Atlantic Monthly. Written by W. E. B. Du Bois, it was titled "The African Roots of War.'" It was a war for empire, of which the struggle between Germany and the Allies over Africa was both symbol and reality: ". . . in a very real sense Africa is a prime cause of this terrible overtuning of civilization which we have lived to see.'" Africa, Du Bois said, is "the Land of the Twentieth Century," because of the gold and diamonds of South Africa, the cocoa of Angola and Nigeria, the rubber and ivory of the Congo, the palm oil of the West Coast.
Du Bois saw more than that. He was writing several years before Lenin's Imperialism, which noted the new possibility of giving the working class of the imperial country a share of the loot. He pointed to the paradox of greater "democracy" in America alongside "increased aristocracy and hatred toward darker races." He explained the paradox by the fact that "the white workingman has been asked to share the spoil of exploiting 'chinks and 'niggers''' Yes, the average citizen of England, France, [and] the United States had a higher standard of living than before. But: "Whence comes this new wealth? . . . It comes primarily from the darker nations of the world - Asia and Africa, South and Central America, the West Indies, and the islands of the South Seas."
Du Bois saw the ingenuity of capitalism in uniting exploiter and exploited - creating a safety valve for explosive class conflict. "It is no longer simply the merchant prince, or the aristocratic monopoly, or even the employing class, that is exploiting the world: it is the nation, a new democratic nation composed of united capital and labor."
The United States fitted that idea of Du Bois. American capitalism needed international rivalry - and periodic war - to create an artificial community of interest between rich and poor, supplanting the genuine community of interest among the poor that showed itself in sporadic movements. How conscious of this were individual entrepreneurs and statesmen? That is hard to know. But their actions, even if half-conscious, instinctive desires to survive, matched into a scheme. And in 1917 this demanded a national consensus of war.