The World at War (1942)

The World at War is a 1942 documentary film produced by the Office of War Information. One of the earliest long length films made by the government during the war, it attempted to explain the large picture of why the United States was at war, and the various causes and circumstances which brought the war into being. It can thus be seen as an anticipation, or trial run of the much better know 6-part Why We Fight propaganda film series directed by Frank Capra.

More at Wikipedia.