The Man from Colorado

In Colorado near the end of the American Civil War, Union Colonel Owen Devereaux (Glenn Ford) orders his regiment to fire on a detachment of Confederate States of America soldiers, even though he (and only he) has seen that they are signaling their surrender with a white flag. Afterward, his best friend and second-in-command, Captain Del Stewart (William Holden), finds the white flag, considers it and then buries it as a surviving Confederate officer secretly looks on.