During World War II, all hands were on deck, even in Hollywood. Many of America and Britain's finest filmmakers, from Hitchcock to Frank Capra, were recruited to create propaganda films to support the war effort. (More on that here.) And the same went for Walt Disney, who turned his lovable cartoon characters into good patriots.
In 1942, Disney released "Der Fuehrer's Face," an anti-Nazi propaganda movie that bolstered support for the war, and eventually won the Academy Award for Best Animated Short Film. Then, a year later, came The Spirit of ’43, which features Donald Duck helping Americans to understand why they need to pay their taxes. Other wartime Disney shorts include Donald Gets Drafted (1942), The Old Army Game (1943), and Commando Duck (1944). Then, coming out of this propaganda tradition, you'll also find Donald Duck Meets Glenn Beck in Right Wing Radio Duck, a recent spoof by Jonathan McIntosh (of Rebellious Pixels). It's a good bit of fun.
Note: Der Fuehrer's Face and The Spirit of ’43 appear in the Animation section of our collection, 1,150 Free Movies Online: Great Classics, Indies, Noir, Westerns, etc..