During the Mexican-American War (1846-48), hundreds of Irish and other immigrant soldiers who faced anti-Catholic sentiment in American society and in the military, deserted the United States Army to fight on the Mexican side. Known as the San Patricio Battalion, they fought in the important battles of Monterrey, Buena Vista, Cerro Gordo, and Churubusco. These soldiers fought with a sense of desperation, knowing full well the horrible punishment that awaited them if they were taken prisoner. In...