Before Orwell's Animal Farm, the Schlesinger studio produced a couple WB cartoons depicting animal versions the rise of the Axis powers. McCabe's THE DUCKTATORS (1942) and Freleng's THE FIFTH COLUMN MOUSE (1943) focus primarily on Hitler's rise to power following a revolt. These carry a morale boosting tone.
There are several parallels between the events of Hitler's rise to power in Germany such as a mouse attempting to appease the cat in order to avoid war. The mice only decide to fight back when the cat turns on them. The nazi imagery is almost nonexistent in this short aside from a couple subliminal references to Hitler and the axis (look closely at the scene of the cat peeking through the foggy window before he enters the basement). This could be why the short was able to be reissued after the war ended.
WWII had some of the most interesting propaganda films that were covered by virtually every film studio. These were very effective in keeping a positive morale on the home front, despite the severity of the situation and the uncertainty of the outcome. I like how this short encourages the audiences to "grit your teeth, show some fight, and the stuff that you're made of; Remember to never say die!" The WWII tune "We Did It Before, and We Can Do It Again" was a nice addition.
The public domain status of this short has made it widely available.