MGM - Peace On Earth

The classic 1939 short that was nominated for an Academy Award. The story takes place in the future, when all humans have died. A family of squirrels are gathered together on Christmas Eve, and the grandfather squirrel is asked who the "men" are in the line "Peace on Earth, goodwill to men" (from the carol I Heard The Bells On Christmas Day). Grandpa then tells the tale of how war-driven humans drove themselves out of existence through all their fighting, the wars only ending when the last human died. Somewhat bleak for a Christmas cartoon, but it carries a good message.