During World War II, Disney created propaganda for the US government. The cartoons dealt with subjects as varied as income taxes, the daily life of Nazis, and military tactics. I've collected a sampling of the cartoons below, for your viewing pleasure and amazement -- be warned, some are pretty weird, and many contain offensive racial or cultural caricatures.
Note that most (all?) of these are included in the DVD box set Disney on the Front Lines, if you're into this kind of thing. I have this set, and the back says: "On December 8, 1941, the Disney Studio was taken over by the military as part of the war effort. Making the most of the talent that hadn't shipped out yet, Walt Disney spent the next four years creating and producing training, propaganda and educational films for the Armed Forces."
Here's a snippet from Wikipedia on Disney's propaganda films:
As requested by the US Government, Walt Disney created a number of anti-German and anti-Japanese films for both the soldiers and the US public. He wanted to portray these countries and their leaders as manipulative without morals. A few of the films he produced were "Der Fuehrer's Face" (1942), "Education for Death - The Making of a Nazi" (1943), and "Commando Duck" (1944). In "Der Fuehrer's Face," Donald Duck breaks down after experiencing a nightmare where he has to make do with eating disgusting Nazi food rations and experiences a day at a Nazi artillery factory. "Education for Death - The Making of a Nazi" was a wartime propaganda film that takes on the perspective of Hans, a young German boy. As the movie progresses and Hans is exposed to Hitler youth and the Nazi culture, his value of human life decreases. In "Commando Duck", Donald, by himself, destroys an entire Japanese airbase.
The Spirit of '43 (Income Tax)
Including an early appearance of Scrooge McDuck, this cartoon shows Donald Duck learning about funding war via the income tax. Representative quote: "Just remember: every dollar you spend for something you don't need is a dollar spent to help the Axis.... And every dollar you sock away for taxes is another dollar to sock the Axis!"
Education for Death - The Making of a Nazi
"What makes a Nazi? How does he get that way?" Creepy to the extreme. The end, showing marching legions, is particularly grim.
Der Fuhrer's Face
Leonard Maltin introduces this cartoon, featuring the song "Der Fuhrer's Face" by Spike Jones. This one won an Academy Award!
A bizarre cartoon featuring fairly typical Donald Duck hijinks...and plenty of racist vilification of the Japanese (including the suggestion that it's a "Japanese custom" to shoot men in the back).
All Together (War Bonds)
Hey, the Canadians get some propaganda too! Unfortunately this one doesn't feature any dialogue, though it does show a parade in front of the Canadian Parliament in Ottawa.
Donald's Decision (War Bonds)
Another production aimed at Canadians (note the flag flying by the post office), this features Donald Duck fighting with his inner demon, who doesn't want him to support the war.
Victory Vehicles (Gas/Tire Shortage)
To deal with shortages in gasoline and tires, Disney suggests you take...a pogo stick. Seriously. Well, maybe not entirely seriously -- but still, a bicycle might be nice.
How to Be a Sailor
A bizarre little movie featuring Goofy learning to be a sailor, ultimately destroying a Japanese fleet.
Got Any More?
There are many more like these -- search YouTube for Disney movies in 1943 and 1944 and you'll find a bunch. There are lots of technical films as well, including the riveting (sorry) Four Methods of Flush Riveting. Actually, I'll spare you: the riveting movie is extremely boring, but the visuals are nicely done.