The Impostor (1944)

A condemned murderer named Clement is "liberated" when the Nazis bomb the French jail that holds him. During his escape, Clement comes across the body of a French soldier; he steals the dead man's uniform and identification papers, then hides from the law by joining the Resistance movement. Clement's new identity and purpose in life reforms him, and in due time he has sacrificed himself in service of his country.