The Golden Strain.

Lt. Milt Mulford graduates from West Point and is assigned to a cavalry outpost in the West, near an Apache reservation. One day the Apaches, tired of being cheated by a crooked Indian agent, break the reservation and Mulford is sent after them with a patrol. Unfortunately, he cracks under the pressure of his first firefight, and is thrown out of the army. His fiancé, disgusted, ends their engagement. He sets out to prove that he is not a coward and regain his fiancé's love.