Riders of the Northland (movie, 1942)

In this western, three Texas Rangers decide to do their part to save the world and join the Army, but before they can, they are sent to Alaska to destroy a secret Nazi operation involving a submarine refueling station. The outpost is located behind an impenetrable tangle of barbed wire. The rangers get a little help, and discover a traitor. Then to get through the wire, they start a cattle stampede and save the day.