The American armed forces perceived the potential benefits of supporting the production of war films when American cinema was still in its early days. Primed during the First World War, intense during the Second World War, relations between the studios and the armed forces slackened during the Vietnam War and were re-activated under Reagan. The success of "Top Gun" opened the way for a new co-operation. Since the 80’s, Hollywood has focussed on past wars, installing its fictions in military bases, aboard submarines and aircraft carriers that the armed forces have generously made available to the studios. In exchange, their experts intervene in the screenplays. Two hundred are submitted to them each year. Through this co-operation, each side is pursuing its own objectives: for the studios, to produce successful films for the least amount of money; for the Pentagon, to improve its image and create interest in careers in the military. Observing these relationships exposes the convulsions and paradoxes of the rise in American power in the 20th century.