Confrontation between U.S. and Mexican troops in April 1847 when U.S. forces under Winfield Scott first met serious resistance in the Mexican War .
As Scott's army marched from Veracruz to Mexico City, it attacked an entrenched Mexican force of 12,000 under Antonio Santa Anna at a mountain pass near Cerro Gordo. Scott's troops routed the Mexicans, who left 1,130 casualties; the U.S. lost 63 men.