The production company Contemporary Historians was set up to raise money for a documentary filmed on the spot. With John Ferno and initially with John Dos Passos, who, when he left the crew, was replaced by Ernest Hemingway, Joris Ivens went to Fuenteduena, near Madrid, to film on the front of the republican armies. It has become one of the major films on the Spanish Civil War and one of the most important films in Ivens's carreer. Like in many other films Ivens finds a balance between the daily life of people and their struggle to survive. The strong photography, mainly by John Ferno, combined with the powerful editing by Helen van Dongen and the commentary of Ernest Hemingway make the film a masterpiece of documentary film making. In a first version the commentary was spoken by Orson Welles, but his voice was considered 'too beautiful' to be combined with the film, so it was decided that Hemingway did himself the commentary.