Frank Capra (May 18, 1897 – September 3, 1991) was a Sicilian-born American film director and a creative force behind a number of films of the 1930s and 1940s, including It Happened One Night (1934), Mr. Deeds Goes to Town (1936), Lost Horizon (1937), You Can't Take It With You (1938), Mr. Smith Goes to Washington (1939), Meet John Doe (1941), Arsenic and Old Lace(1944) and It's a Wonderful Life (1946). During World War II, Capra directed or co-directed ten documentary propaganda films between 1942 and 1948, as a major in the U.S. Army. These films include the seven-episode U.S. government-commissioned Why We Fight series—consisting of Prelude to War (1942), The Nazis Strike (1942), The Battle of Britain (1943), Divide and Conquer (1943), The Battle of Russia (1943), The Battle of China (1944). The Why We Fight films are considered to be positive use of propaganda. Capra considered them his most important works, and for them, he won an Oscar.
While this propaganda was meant to stir the patriotism of those who favored neutrality and isolationism, they are interesting. IF you have time...consider watching the Battle of Britain film. It's well worth it.
The majority of the text of this post is paraphrased. from the Wikipedia article on Frank Capra. The entry includes an extensive bibliography and references.