The Man from Colorado

The Man from Colorado is a 1948 American westernpsychological drama film directed by Henry Levin and produced by Jules Schermer for Columbia Pictures. It stars Glenn Ford as a Union officer who becomes addicted to killing during the American Civil War, William Holden as his best friend, and Ellen Drew as their common love interest. Robert Andrews and Ben Maddow based the screenplay on a story by Borden Chase.

Immediately after the battle, the war ends. As the soldiers celebrate, Sergeant Jericho Howard James Millican gets drunk while on duty and is insubordinate to Devereaux, who has him arrested. At a ball, the mayor announces Devereauxs appointment as the federal judge for the region. Stewart asks Caroline Emmett Ellen Drew to marry him, but she later marries Devereaux instead.When the Confederate survivor confronts Devereaux about the white flag, Devereaux shoots him, even though the man has already been subdued. Stewart realizes that Devereaux must have seen the flag and concludes that the war has unhinged Devereauxs mind. He agrees to serve as Devereauxs marshal after Devereaux promises not to participate in arrests. ........

Source: Wikipedia