about the need for vigilance, too, as in Went the Day Well? (1942) or the avoidance of "careless talk", as in The Next of Kin (1942). In America, Charlie Chaplin's The Great Dictator (1940) clearly satirised fascism. Michael Curtiz's Casablanca (1943) was not simply a romance between the characters played by Humphrey Bogart and Ingrid Bergman, but vilified the Nazis and glorified resistance to them. Frank Capra's Why We Fight series (1942–1945) won the 1942 Academy Award for best documentary, though it was designed to "influence opinion in the U.S. military". During the Cold War, "propaganda played as much of a role in the United States' struggle with the Soviet Union as did the billions of dollars spent on weaponry." Face to Face with Communism (1951) dramatised an imagined invasion of the United States; other films portrayed threats such as communist indoctrination. Submarine Submarine films have their own particular meanings and conventions, concerned specifically with giving the effect of submarine warfare. A distinctive element in this subgenre is the soundtrack, which attempts to bring home the emotional and dramatic nature of conflict under the sea. For example, in Wolfgang Petersen's 1981 Das Boot, the sound design works together with the hours-long film format to depict lengthy pursuit with depth charges, the ping of sonar, and threatening sounds such as of the propellers of enemy destroyers and torpedoes. Classic films in the genre include The Enemy Below (1957) and Run Silent, Run Deep (1958), both based on novels by naval commanders. Run Silent, Run Deep is a movie full of tension, both with the enemy and between the contrasting personalities of the submarine Commander and his Lieutenant, played by Clark Gable and Burt Lancaster. Prisoner of war A popular subgenre of war films in the 1950s and 1960s was the prisoner of war film. The genre was popularised in Britain with major films like Guy Hamilton's The Colditz Story (1955) and John Sturges's American film The Great Escape (1963). They told stories of real escapes from German prisoner of war camps such as Stalag Luft III in the Second World War. Despite episodes of danger and human tragedy, these films delight in a continual boyish game of escape and ingenuity, celebrating the courage and the defiant spirit of the prisoners of war, and treating war as fun. David Lean's Bridge on the River Kwai (1957) was judged best picture at the