As people in America were experiencing prosperity and freedom, news started filtering through about the war happening overseas. With the German military quickly overcoming defenses in places like Holland, Belgium, Luxembourg, and France, the U.S. government began to recognize weaknesses in its own capacity for protection. President Roosevelt tried to strengthen the armed forces by significantly increasing investment in the navy and air force, while also improving training and recruitment efforts for an army that seemed far too small for what might be needed. Then came December, and the United States found itself pulled into a conflict that had grown much larger than they’d previously imagined. The film has a propagandistic feel, but it doesn't just overtly promote a message; instead, it suggests what could be necessary from everyday citizens and cautions that without personal sacrifice and hard work, everything valued might disappear. There’s a good amount of historical footage included, and some of it frankly shows the brutality of those advancing as well as how ill-prepared the country was, relying on things like discarded beer cans and outdated vehicles to get troops ready for battle. The final message is quite forceful.

Source on TMDB