John Wayne and Rock Hudson co-star in this rollicking classic set in Mexico during the tumultuous post-Civil War days. As Union Cavalry officer John Henry Thomas (John Wayne) and former Confederate Colonel James Langdon (Rock Hudson) lead their men into new territories to begin a new life, their paths cross. Now, caught between Mexican rebels and the Emperor's forces, they find themselves fighting side by side and must forge an uneasy friendship in order to survive. Based on a story by Stanley L. Hough, this entertaining film about unlikely alliances is Western action at its best.

After the Civil War, former Union Colonel John Henry Thomas (John Wayne) and Confederate Colonel James Langdon (Rock Hudson) are leading expeditions to Mexico, where Langdon will establish a new settlement away from Carpetbaggers and Thomas will sell horses. Along the way they must put aside their differences to deal with a threatening Mexican general. THE UNDEFEATED also features Los Angeles Rams stars Merlin Olson and Roman Gabriel.