?was the title of a Loyalist propaganda film he wrote a comment for. Supporting the -mostly Communist- Loyalists further, he and John Dos Passos went to Spain, founded the Contemporary Historians, Inc. which produced another film called "The Spanish Earth". In addition to that, Hemingway became war correspondent for NANA, the North American Newspaper Alliance, thus he saw much of the fighting and could collect experiences for a new novel. While he was in Spain, his second marriage went to pieces. A liaison with Martha Gellhorn was revealed when a Rebel shell hit the hot-water boiler of the correspondents' hotel "Florida".
After "The Spanish Earth" was boxed and shipped, he left with the promise to propagandize for the Loyalists' cause. He spoke out in Shakespeare & Co. and addressed the Writers' Congress in New York on the fourth of June 1937. In his speech he stressed he was anti-fascist, not pro-Communist(Writer As Artist (7.), p. 224)
There is only one form of government [...] that cannot produce good writers, and that system is fascism. For fascism is a lie told by bullies. A writer who will not lie cannot live and work fascism.
Due to his reputation, "The Spanish Earth" was even shown in the White House and his article "Fascism is a Lie" was published in "New Masses". Furthermore, he established an ambulance fund and financed it by collecting money at Hollywood parties.
He returned to see Franco control two thirds of Spain, the Loyalists still fought on. "The Fifth Column" was finished just before the taking of Teruel in January 1938. He wrote it, according to the preface, under constant bombardment in the Hotel Florida, it appears as though he had again needed the thrilling aura of death to inspire him.
After short stays in Paris due to liver troubles and in Key West, he came back to Spain to see Loyalists retreating on all fronts, then returned to America to organize the experiences he gathered into a novel, the narrations of the different characters clearly originate here.