Despite the crushing defeat at Buena Vista (February 1847), the Mexican government refused to surrender. In March, General Winfield Scott gathered a 10,000 man force in southern Texas before sailing down the Gulf coast. He landed near the port city of Vera Cruz and successfully besieged the town. He later began a 260-mile march toward Mexico City, following basically the same path as Cortes centuries earlier.
In a truly classic campaign, Scott managed to preserve his force and steadily advance. He was victorious in the mountains at Cerro Gordo in April 1847, and later at Puebla in May.
Then followed the August Armistice, a two-week truce during which the Americans again sought Mexican capitulation. Again they were rebuffed. Santa Anna used the time to strengthen his defenses.
Warfare resumed and the American force pushed on toward Mexico City. U.S. victories were won at Contreras (August 19-20) and Churubusco (August 20), where Santa Anna defended a position from within a convent. Heavy American casualties were sustained at Molino del Rey (September 7-8).
The last major engagement occurred at the fortified hill position of Chapultepec. Bombardment of the position began on September 12. An inspired defense was mounted by young cadets of the Mexican Military College, but they were eventually forced to give way, which opened the road to Mexico City. Surrender occurred on September 13, 1847. Santa Anna abdicated shortly thereafter and fled the country.
Scott's offensive is regarded by many as the greatest in American military history. His forces achieved their object despite overwhelming obstacles, including extreme heat, insufficient supplies, widespread disease as well as intense enemy opposition in unfamiliar territory.