During the Sioux Wars, General Frederick McCabe's 3rd U. S. Cavalry Regiment recruits and trains men for the upcoming campaign against the Sioux. Captain Demas Harrod is in charge of the D troop. He's also in love with pretty Lou Woodard who lives in Mule City and is engaged to Sol Rogers, chief of scouts under General McCabe. She claims to be attracted to both men, which brings the two rivals into conflicts that often end up in fist-fights. At the fort, the training of men intensifies. After the graduation, the troopers get a well-deserved leave which they spend in nearby Mule City drinking heavily and causing disturbances. These disturbances prompt the town Marshal and his deputies to try to arrest the rowdy soldiers. A general fist-fight ensues, bringing Captain Harrod and chief of scouts Rogers together on the same side of the match. General McCabe participates in a commanders' briefing to devise a plan of attack against the Sioux. McCabe is ordered to advance his regiment to a rendezvous point and wait for General Hoffman's regiment. He's told to refrain from attacking the Sioux without Hoffman's support. But General McCabe, ambitious and dreaming of glory, secretly decides to rush his troops to arrive at their predetermined destination a day early. He intends to attack the Sioux without General Hoffman's assistance and therefore claim all the glory for himself. Unknown to him, the Sioux forces are much larger than previously estimated. General McCabe and his troops are in mortal danger.