The invasion of Northeastern Mexico
After Zachary Taylor’s defeat of the Mexican troops north of the Rio Grande he led his army into Mexico and laid siege to the city of Monterrey. Monterrey was fortified with many battlements built of stone, and the American artillery, which had been effective against the Mexican troops at Palo Alto and Resaca, was unable to reduce them. For the first time, American infantry was forced to engage in urban warfare, fighting house to house in an attempt to capture the city. The infantry was forced to engage houses one at a time, either entering through windows or using demolitions to batter down the walls in order to engage their enemy in fighting which was often hand to hand.
Casualties were heavy among the American troops, but gradually Mexican forces were driven back. They prepared a final stand in the city near its public buildings in the town’s main square, where American artillery could reach them in the open. The Mexicans surrendered on September 24, and Taylor allowed the remaining Mexican troops to withdraw, granting an armistice of eight weeks during which the Mexicans agreed to cease hostile actions against American positions. Taylor needed the respite to rest his own exhausted forces. The American army had cleared the larger Mexican army from a well-fortified position and captured a significant prize.
Despite Taylor’s clear victory, Polk was furious when he was informed of the armistice. He was also concerned over the rise in Taylor’s popularity following his third major defeat of the enemy. Polk announced that Taylor had no authority to grant an armistice or any other form of cease fire, and ordered his general to advance against the enemy. At the same time the opposition press in the United States reported atrocities committed by the American troops in Monterrey and neighboring towns and hamlets, which Taylor did not bother to deny. Instead the reported rapes and murders of civilians were blamed on volunteer troops, rather than the American regulars.
With Polk demanding action, Taylor violated the armistice and moved units of his army further south, seizing Saltillo, and creating a fortified position in the mountains at Buena Vista. Santa Anna moved north to attack him, at the head of an army of 20,000 men. Taylor had less than five thousand troops. The Mexican Army endured significant numbers of deserters as it moved to the north, by the time it reached Taylor’s lines it had lost nearly 5,000 men. Still, it outnumbered the Americans by a factor of three to one, and Santa Anna, with the flamboyance for which he was known, demanded that the Americans surrender.
The ensuing Battle of Buena Vista was a victory of superior American firepower, from both artillery and infantry. The Mexican assaults were repulsed despite their overwhelming numbers, and the American line held throughout the afternoon of February 22, 1847. The battle was fought in a narrow mountain pass, which limited the ability of the Mexican army to maneuver into advantageous positions. The following day the American lines again held against repeated Mexican assaults. When Santa Anna broke off the attacks and withdrew, Taylor did not pursue the still larger Mexican force. It was yet another victory for Zachary Taylor, and he was celebrated in the United States as America’s foremost soldier.