"Mice Declare War on Cats," says the newspaper headline. "All Cats Called to the Colors." And they mean it. A recruiter forces Felix to enlist. Soon, Felix is at the front, doing his best to duck his duty when he isn't ducking cannonballs. Felix's gas mask saves him from being gassed to death by smelly cheese. But his life is continually in danger. He gets the bright idea to hide in a cannon, but inevitably a fellow soldier fires it, which propels Felix into the camp of the dreaded mice. Felix manages to escape their firing squad with some last-minute hi-jinks. Finally, he spots a newspaper that says, "Married Men Will Be Exempt from Duty at the Front." Felix immediately finds a pretty girl, proposes marriage to her and rushes her to the church. But after the honeymoon, poor Felix the Cat discovers that war is only heck; it's marriage that's hell.