The Spanish Civil War was a cause celebre among literary liberals, who saw Francisco Franco's attack against the Third Republican Government in Spain in 1936 as a fascist assault against socialist ideals, with international implications. The German and Italian governments supported Franco with arms and supplies, and the Soviet Union backed the Republican government. John Dos Passos, a Communist fellow traveler who had lived in Spain and had close friends there, felt compelled to tell the world, about the conflict in Spain. When his efforts to create a news service to report the war from the perspective of the ordinary Spaniard failed, he conceived the idea of a documentary movie that would explain the effect of the war on Spanish peasants and marshall support for the Republican cause.

Late in 1936 a group called Contemporary Historians was formed to develop the idea for a documentary...