The Siege at Red River

In the closing days of the Civil War, Confederate Captain Jim Farraday (Van Johnson) steals a shipment of Gatling guns from the Northern army, and by pretending to be the proprietor of a traveling medicine show, manages to smuggle the guns back through enemy lines. However, when disloyal Rebel Brett Manning (Richard Boone) steals the guns from him with a plan to sell them to the Indians, Farraday surrenders to the Union in order to enlist their help getting the weapons back.