Mexican-American War: Battle of Chapultepec

Fighting for Chapultepec, 1847
Public Domain

The Battle of Chapultepec was fought September 12 to 13, 1847, during the Mexican-American War (1846 to 1848). With the start of the war in May 1846, American troops led by Major General Zachary Taylor scored quick victories at the Battles of Palo Alto and Resaca de la Palma before crossing the Rio Grande to strike the fortress city of Monterrey. Assaulting Monterrey in September 1846, Taylor captured the city after a costly battle. After the Monterrey's capitulation, he annoyed President James K. Polk when he gave the Mexicans an eight-week armistice and permitted Monterrey's defeated garrison to go free. 

With Taylor and his army holding Monterrey, debate commenced in Washington regarding American strategy moving forward. Following these conversations, it was decided that a campaign against the Mexican capital in Mexico City would be critical to winning the war. As a 500-mile march from Monterrey over difficult terrain was recognized as impractical, the decision was made to land an army on the coast near Veracruz and march inland. This choice made, Polk was next required to select a commander for the campaign.

Scott's Army

Though popular with his men, Taylor was an ardent Whig who had publicly criticized Polk on several occasions. Polk, a Democrat, would have preferred a member of his own party, but lacking a qualified candidate, he chose Major General Winfield Scott. A Whig, Scott was seen as posing less of a political threat. To create Scott's army, the bulk of Taylor's veteran units were directed to the coast. Left south of Monterrey with a small force, Taylor successfully defeated a much larger Mexican force at the Battle of Buena Vista in February 1847.

Landing near Veracruz in March 1847, Scott captured the city and began marching inland. Routing the Mexicans at Cerro Gordo the following month, he drove towards Mexico City winning battles at Contreras and Churubusco in the process. Nearing the edge of the city, Scott attacked the Molino del Rey (King's Mills) on September 8, 1847, believing there to be a cannon foundry there. After hours of heavy fighting, he captured the mills and destroyed the foundry equipment. The battle was one of the bloodiest of conflict with the Americans suffering 780 killed and wounded and the Mexicans 2,200.

Next Steps

Having taken Molino del Rey, American forces had effectively cleared many of the Mexican defenses on the western side of the city with the exception of Chapultepec Castle. Situated atop a 200-foot hill, the castle was a strong position and served as the Mexican Military Academy. It was garrisoned by fewer than 1,000 men, including the corps of cadets, led by General Nicolás Bravo. While a formidable position, the castle could be approached via a long slope from Molino del Rey. Debating his course of action, Scott called a council of war to discuss the army's next steps.

Meeting with his officers, Scott favored assaulting the castle and moving against the city from the west. This was initially resisted as the majority of those present, including Major Robert E. Lee, desired to attack from the south. In the course of the debate, Captain Pierre G.T. Beauregard offered an eloquent argument in favor of the western approach which swung many of the officers into Scott's camp. The decision made, Scott began planning for the assault on the castle. For the attack, he intended to strike from two directions with one column approaching from the west while the other struck from the southeast.

Armies & Commanders

United States

  • Major General Winfield Scott
  • 7,180 men


  • General Antonio Lopez de Santa Anna
  • General Nicholas Bravo
  • around 1,000 men near Chapultepec

The Assault

At dawn on September 12, American artillery began firing on the castle. Firing through the day, it halted at nightfall only to resume the next morning. At 8:00 AM, Scott ordered the firing to stop and directed the attack to move forward. Advancing east from Molino del Rey, Major General Gideon Pillow's division pushed up the slope spearheaded by an advance party led by Captain Samuel Mackenzie. Advancing north from Tacubaya, Major General John Quitman's division moved against Chapultepec with Captain Silas Casey leading the advance party.

Pushing up the slope, Pillow's advance successfully reached the walls of the castle but soon stalled as Mackenzie's men had to wait for the storming ladders to be brought forward. To the southeast, Quitman's division encountered a dug-in Mexican brigade at the intersection with the road leading east into the city. Ordering Major General Persifor Smith to swing his brigade east around the Mexican line, he directed Brigadier General James Shields to take his brigade northwest against Chapultepec. Reaching the base of the walls, Casey's men also had to wait for ladders to arrive.

Ladders soon arrived on both fronts in large numbers allowing the Americans to storm over the walls and into the castle. The first over the top was Lieutenant George Pickett. Though his men mounted a spirited defense, Bravo was soon overwhelmed as the enemy attacked both fronts. Pressing the assault, Shields was severely wounded, but his men succeeded in pulling down the Mexican flag and replacing it with the American flag. Seeing little choice, Bravo ordered his men to retreat back to the city but was captured before he could join them.

Exploiting the Success

Arriving on the scene, Scott moved to exploit the capture of Chapultepec. Ordering Major General William Worth's division forward, Scott directed it and elements of Pillow's division to move north along the La Verónica Causeway then east to assault the San Cosmé Gate. As these men moved out, Quitman re-formed his command and was tasked with moving east down the Belén Causeway to conduct a secondary attack against the Belén Gate. Pursuing the retreating Chapultepec garrison, Quitman's men soon encountered Mexican defenders under General Andrés Terrés.

Using a stone aqueduct for cover, Quitman's men slowly drove the Mexicans back to the Belén Gate. Under heavy pressure, the Mexicans began to flee and Quitman's men breached the gate around 1:20 PM. Guided by Lee, Worth's men did not reach the intersection of the La Verónica and San Cosmé Causeways until 4:00 PM. Beating back a counterattack by Mexican cavalry, they pushed towards the San Cosmé Gate but took heavy losses from the Mexican defenders. Fighting up the causeway, American troops knocked holes in the walls between buildings to advance while avoiding Mexican fire.

To cover the advance, Lieutenant Ulysses S. Grant hoisted a howitzer to the bell tower of the San Cosmé church and began firing on the Mexicans. This approach was repeated to the north by US Navy Lieutenant Raphael Semmes. The tide turned when Captain George Terrett and a group of US Marines were able to attack the Mexican defenders from the rear. Pushing forward, Worth secured the gate around 6:00 PM.


In the course of the fighting at the Battle of Chapultepec, Scott suffered around 860 casualties while Mexican losses are estimated at around 1,800 with an additional 823 captured. With the city's defenses breached, Mexican commander General Antonio López de Santa Anna elected to abandon the capital that night. The following morning, American forces entered the city. Though Santa Anna conducted a failed siege of Puebla shortly thereafter, large-scale fighting effectively ended with Mexico City's fall. Entering into negotiations, the conflict was ended by the Treaty of Guadalupe Hidalgo in early 1848. The active participation in the fighting by the US Marine Corps led to the opening line of the Marines' Hymn, "From the Halls of Montezuma..."

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Hickman, Kennedy. "Mexican-American War: Battle of Chapultepec." ThoughtCo, Apr. 5, 2023, Hickman, Kennedy. (2023, April 5). Mexican-American War: Battle of Chapultepec. Retrieved from Hickman, Kennedy. "Mexican-American War: Battle of Chapultepec." ThoughtCo. (accessed June 3, 2023).