The Battle of Monterrey (September 21–September 23, 1846) was an engagement in the Mexican-American War in which General Pedro de Ampudia and the Mexican Army of the North managed to fight US troops to a standstill at the important fortress town of Monterrey.

After a number of embarrassing defeats and near misses, the Army of the North attempted to retreat south and refit before engaging the seemingly unbeatable US forces under General Zachary Taylor. Near the old fortress town of Monterrey, General Pedro de Ampudia received orders from Antonio López de Santa Anna to retreat further to the city of Saltillo where Ampudia was to establish a defensive line. But Ampudia, who was hungry for victory and conscious that his men were nearing mutiny through constantly being forced to retreat, refused the order and chose instead to make a stand at Monterrey. Joining Ampudia at this engagement were an elite artillery unit, the largely Irish-American San Patricios (or the Saint Patrick's Battalion), in their first major engagement against US forces.

For three days, US forces attempted to take the city without success. Heavy Mexican resistance caused considerable losses in the US ranks, and the US artillery found itself incapable of penetrating the walls of the numerous fortresses and fortifications in the area. Finally, the invaders drew close enough to the city to use their only piece of siege artillery, a somewhat antiquated Napoleonic era 32-pound siege howitzer that began to hurl rounds into Monterrey's central plaza, panicking the local inhabitants.

On the night of the 23rd, a final US push to capture the city walls met with fierce resistance, particularly on the part of the San Patricios. The US line, near to cracking, began a somewhat disorganized retreat. At the same time, Zachary Taylor, determined to win the day, ordered his mortar to begin shelling indiscriminately. This act finally broke the back of the Mexican resistance and, with the US forces in full retreat, Ampudia ordered the white flag of surrender to be flown.

The resulting armistice signed between Taylor and Ampudia had major effects upon the outcome of the war. Taylor was lambasted by Washington, where President James K. Polk insisted that the US army had no authority to negotiate truces, only to "kill the enemy". In addition, his terms of armistice, which allowed Ampudia's forces to retreat with battle honors and all of their weapons, were seen as foolish and short-sighted by some US observers.

For his part, some have argued that Ampudia had sown the seeds of defeat for Mexico. Many Mexican soldiers became depressed and disenchanted. In a well fortified, excellently supplied position, an army of twelve thousand Mexican soldiers had nearly defeated the US Army, only to be forced to surrender at their moment of triumph. Many felt that their generals simply did not want to win, and desertions and mutiny became widespread problems.

See also

• Battles of the Mexican-American War

References

Bauer, K. Jack, "The Mexican War, 1846-1848"