Hail the Conquering Hero (1944)

Having been discharged from the Marines for a hayfever condition before ever seeing action, Woodrow Lafayette Pershing Truesmith (Eddie Bracken) delays the return to his hometown, feeling that he is a failure. While in a moment of melancholy, he meets up with a group of Marines who befriend him and encourage him to return home to his mother by fabricating a story that he was wounded in battle with honorable discharge. They make him wear a uniform complete with medals and is pushed by his new friends into accepting a Hero's welcome when he gets home where he is to be immortalized by a statue that he doesn't want, has songs written about his heroic battle stories, and ends up unwillingly running for mayor. Despite his best efforts to explain the truth, no one will listen.