However, the story at Chapultepec cemented itself in Mexican history, as an act of bravery by six young cadets known as the Niños Héroes, who leapt to their deaths rather than die at the hands of American forces.

He had fought a major battle at Cerro Gordo but had encountered little resistance in capturing Mexico's second-largest city, Puebla.

Scott avoided the direct route from Puebla to Mexico City due to the heavily defended road to El Peñon.

The Mexican defenders blocked the route to the capital at Hacienda of San Antonio, with marshes to their north and a lava field to the south, known as the Pedregal.

[5] On September 8, 1847, Scott ordered William Worth to use his force of 3,250 men against the Molino del Rey building, approximately 1,000 yards from the castle itself.

[2] This was known as the costly Battle of Molino del Rey, where U.S. forces had managed to drive the Mexicans from their positions near the base of Chapultepec Castle guarding Mexico City from the west.

[2]: 311  Mexico City was fortified with a series of canals and gates serving as customs checkpoints and Scott favored attacking Chapultepec; and only General David E. Twiggs agreed.

[2]: 312  A young lieutenant, P. G. T. Beauregard, gave a speech that persuaded General Franklin Pierce to change his vote in favor of the Western attack.

[2] By the time US forces approached Chapultepec, American victories had significantly depleted the Mexican army's artillery reserves.

Mexican accounts note the inferior quality of their clothing, citing outdated muskets and poorly constructed cannons.

This group was joined by several recently graduated cadets who had not yet been assigned to the National Army, as well as 19 administrative personnel, including the director, instructors, teachers, and even the school's quartermaster.

Santa Anna, with part of the army, was repelling another attack at the entrance to the Chapultepec Forest, east of the hill, and failed to realize that the main assault on the castle was coming from the west until it was too late.

The San Blas Battalion, with only 400 men, faced the divisions of Worth, Quitman, and Pillow at the foot of the hill, fighting until nearly all were killed.

Santa Anna consulted with Nicolás Bravo, confessing to him that many of his demoralized troops were also likely to melt away if sent into a situation that would result in high casualties.

[11][2]: 313  The first party consisted of Captain Samuel Mackenzie's 256 men from Gideon Pillow's division, who would advance from the Molino east up the hill.

[2]: 316 Pillow was shot in the foot and called for reinforcements, which came from John A. Quitman's division, but the attack faltered when fired upon by the Morelia Battalion battery.

[2]: 318  Santa Anna watched the Americans take Chapultepec, while an aide exclaimed, "let the Mexican flag never be touched by a foreign enemy".

[9] During the battle, five Mexican military cadets, and one of their instructors, refused to fall back when General Bravo ordered a retreat; they fought to the death.

[9] The official narrative about their actions, first promoted in 1852 and gaining greater prominence during the Porfiriato and in 1947, was shaped with nationalist purposes, turning their story into a heroic myth.

Their remains are said to be interred at the Altar to the Fatherland, a site intended to solidify the Niños Héroes' place in Mexican memory.

During General Zachary Taylor's campaign along the Rio Grande, a significant number of U.S. soldiers, deserted and fled to Mexico.

Thirty men from the Saint Patrick's Battalion, a group of former United States Army soldiers who joined the Mexican side, were executed en masse during the battle for their desertion.

[3] The fall of Chapultepec led to a key engagement known as the Battle of San Belen and Cosme Gate, which was part of the U.S. assault on Mexico City in September 1847.

Worth's division was sent by Scott to support Trousdale's men on La Verónica Causeway (now Avenida Melchor Ocampo) for the main attack against the San Cosme Gate.

Meanwhile, General Quitman quickly gathered the troops in Chapultepec, except the 15th Infantry, who guarded the castle and prisoners, and designed as a feint, headed down the Belén Causeway, stopping at the Belen Garita.

[2]: 320  Lieutenant Ulysses S. Grant, and some 4th Infantry used the bell tower of San Cosme Church south of the causeway to place a mountain howitzer.

[2]: 320  Lt. George Terrett then led a group of U.S. Marines behind the Mexican defenders, and climbing to the roof, unleashed a deadly volley on the artillery gunners.

Several lower-ranking U.S. Army officers participating in the invasion became key generals on both sides of the American Civil War, including Ulysses Grant, Daniel H. Hill, George Pickett, James Longstreet, John C. Pemberton, Thomas Jonathan "Stonewall" Jackson, James J. Archer, P. G. T. Beauregard, and Robert E. Lee.

The Niños Héroes ("Boy Heroes") were considered martyrs fighting to maintain Mexico's honor as a nation and they are celebrated on September 13th.

[9] In 1947, President Harry S. Truman laid a wreath on the 1881 cenotaph of the Niños Héroes as a gesture of goodwill after Mexico aided the U.S. in World War II.