Two young squirrels ask their grandfather (Voiced by Mel Blanc-uncredited) on Christmas Eve who the "men" are in the lyric "Peace on Earth, good will to men." The grandfather squirrel then tells them a history of the human race, focusing on the never-ending wars men waged. Ultimately the wars do end, with the deaths of the last men on Earth, two soldiers shooting each other, one shoots the other soldier and the injured soldier kills the last, but dies as he sinks into watery foxhole as his hand grasp into water. Afterwards, the surviving animals discover a copy of an implied Bible in the ruins of a church. Inspired by the book's teachings, they decide to rebuild a society dedicated to peace and nonviolence (using the helmets of soldiers to construct houses). The cartoon features an original song written to the tune of "Hark! The Herald Angels Sing."
Fred Quimby, William Hanna and Joseph Barbera remade the cartoon in CinemaScope in 1955. This post-WW2 version of the film, entitled Good Will to Men, featured updated and even more destructive forms of warfare technology such as flamethrowers, bazookas, missiles and nuclear weapons. This version used a choir of mice as the main characters including a[Deacon mouse who tell the story to his charges (voiced by Daws Butler-uncredited), and also had more direct religious references (though the Bible is simply referred to as the book of humans' rules in both, Good Will to Men includes a reference to the New Testament, while Peace on Earth only includes verses from the Old Testament). This new version was also nominated for the Best Animated Short Subject Oscar, but unlike the original, it was not nominated for a Nobel Peace Prize. This was the only non-Tom and Jerry CinemaScope cartoon short to be produced by Fred Quimby before he went into retirement.