Military Campaigns

by Drew VandeCreek, Ph.D.

American military forces took up several major campaigns in the course of the Mexican War. Polk began his prosecution of the war in June of 1846 by ordering American forces farther into Mexican territory. He directed Taylor and his men to push southward from the Rio Grande into central Mexico. At the same time Brigadier General Stephen Kearney led a small force overland from Fort Leavenworth, Kansas to seize Santa Fe and the New Mexico territory. Finding little opposition in New Mexico, Kearney marched west to California. There he met up with an American naval force and eventually secured the work of the Bear Flag Revolt, in which American settlers had already declared their independence from Mexico. Finally, a third force under the command of General John E. Wool marched from San Antonio, Texas to the Mexican city of Chihuahua.

General Taylor's force participated in the first significant engagement of the conflict at Monterrey in September of 1846. Taylor boldly divided his force and took the city on September 24. After negotiations, the two sides agreed upon an eight-week armistice during which each general would correspond with his government and await further orders.

President Polk had hoped that a set of quick American victories would compel the Mexican government to bargain away their northern territories. But the Mexicans gave no evidence of capitulating. The president ordered General Taylor to resume operations. But he had decided against marching across the rugged central Mexican terrain to Mexico City. Instead, he ordered Taylor to send his regulars to Tampico on the Gulf of Mexico, where they would come under the command of General Winfield Scott and proceed toward Mexico City from the east. Wool was ordered to abandon his march on Chihuahua in order to reinforce Taylor's depleted commands. A new force, led by Colonel Alexander Doniphan, left Santa Fe and proceeded toward Chihuahua.

While the American forces in central Mexico changed strategies, Mexicans in California and New Mexico struck back in attempts to throw off American occupation. In California the arrival of Kearney's force enabled Americans to defeat Mexican Californios at the Battle of San Gabriel and occupy Los Angeles, effectively ending the conflict there. In New Mexico, American troops under the command of General Sterling Price defeated Mexican rebels at Taos after they had killed officials of the new American government.

Mexican forces counterattacked in February of 1847 at Buena Vista, where they confronted the remainder of Taylor's army and Wool's reinforcements. After using his numerical superiority to batter Taylor's Americans, General Antonio Lopez de Santa Anna inexplicably retreated from the field, allowing Taylor to claim victory.

Winfield Scott's new force opened the final phase of the Mexican-American War when they landed unopposed at Veracruz and occupied the city. As his army marched westward, Scott learned that Santa Anna's forces had dug in at a mountain pass called Cerro Gordo, effectively blocking their path to Mexico City. Advance scouts including Captain Robert E. Lee of Virginia discovered a path around Santa Anna's right flank that allowed American soldiers to circle behind and surprise the enemy. Other American units had succeeded in dragging several artillery pieces to a high point that overlooked the Mexican fortifications. On April 18 Scott's army routed the Mexicans from their positions and cleared the way to the Mexican capital.

After this victory Scott spent three months refitting his army in the Mexican city of Puebla. Many of his soldiers, at the end of their one-year enlistments, returned to their homes. Lacking enough soldiers to continue fighting, Scott waited for reinforcements. Wracked by confusion and retreating toward their capital, the Mexican Army failed to attack Scott's depleted corps.

In August of 1847 Scott turned his rebuilt Army toward Mexico City. Attacking from the south in order to avoid a heavily armed fortress blocking his path, Scott won victories at Contreras and Churubusco. Aware that his army was shrinking rapidly, largely due to the toll taken by subtropical diseases, Scott pressed for a quick conclusion to the fighting. On the morning of September 13, American forces took Chapultepec Castle on the capital's western flank. By that evening they had arrived at the gates to the city, only to find that Santa Anna's forces had evacuated to fight another day.

In the following months Mexican officials carried out a guerilla war, attacking American supply lines. The day after Scott's seizure of Mexico City, Mexican forces laid siege to the American supply depot and hospitals at Puebla. Hoping to force Scott to abandon Mexico City in order to secure his supply base, Santa Anna's remaining troops soon joined the siege. Although Scott had been unable to correspond with Washington due to his insecure supply and communication lines, Polk had wisely sent reinforcements to his commander. These forces arrived at Puebla on October 12 and broke the siege, effectively ending the Mexican-American War.