The Spanish Civil War occupies a very relevant place in the collective memory of Europeans. At the beginning of the War, Spanish filmmaker Luis Buñuel received instructions from the Spanish Ministry of Foreign Affairs to return to Paris and assist the Spanish embassy in various types of counterintelligence and propaganda work. As part of this, Buñuel organized and assembled footage of the Republicans. Unlike other productions compiled in Spain, the Republican propaganda films made in Paris were generally addressed at audiences in different European countries with the aim of breaking the doctrine of non-intervention in the conflict, and they reflect Buñuel’s theories and conception of the documentary films. These films represent good examples of ethical propaganda and their aim was more informative than manipulative. From this standpoint, and in accordance with other research on public relations discourse and film, we argue that the films supervised by Buñuel in this period, and especially the most noteworthy documentary España leal en armas (1937), are examples of public relations films in wartime.