This clip was taken from "Prelude To War, directed by Frank Capra.
Prelude to War was the first film of Frank Capra’s Why We Fight propaganda film series, commissioned by the Office of War Information (OWI) and George C. Marshall. It was made to convince American troops of the necessity of combating the Axis Powers during World War II. The film was based on the idea that those in the service would be more willing and able fighters if they knew the background and reason for their participation in the war. It was later released to the general American public as a rallying cry for support of the war.