After his victory at Vera Cruz Scott advanced with his army towards Mexico City. Blocking him was Santa Ana with 20,000 troops. Santa Ana attempted to block Scott at the pass at Cerra Gordo. Thanks to a successful scouting mission by Captain Robert E Lee, the American forces were able to outflank Santa Ana, and force his troops to withdraw.
After Scott's victory at Vera Cruz he quickly made plans for a march on Mexico City. Scott had 8500 men when he set out. Blocking his way stood Santa Anna with 12,000 men. Santa Anna placed his men along a pass at Cerro Gordo. It was thought that there was no way around the pass. Santa ana placed his men and artillery so that they could control the pass. In addition he placed some guns on El Elegrafo a summit that commanded the area. On April 12 the first elements of the American forces commanded by General Twiggs, arrived. Luckily for Twiggs and his forces the Mexicans opened fire too early and thus Twiggs was able to extract his men.
Scott in the meantime hurried forward to take command of the forces. Scott ordered extensive reconnaissance, one of those carrying out the survey was Captain Robert E Lee, who discovered a trail around the Mexican flank. Scott sent General Twiggs and Shiled on the flanking maneuver, while Gideon Pillow made a noisy demonstration with a force in front of Mexican lines.
Twiggs followed the tail half way and then turned and climbed a hill called Atalaya, which he thought was unguarded. Twiggs found encounter limited opposition but his forces were able to capture the hill and hold it despite Mexican counterattacks. Twiggs was able to carry howitzers to the top of the hill. The next morning Twiggs forces began an attack on Mexican lines. This attack took place as Pillows forces launched a diversionary attack on . Twiggs attack encountered stiff resistance but his men pressed on. At the right moment Shields arrived at a point in the rear of the enemy lines. With their retreat cut off, the Mexican forces panicked. American forces broke into the Mexican fortifications. The Mexican surrendered. American lost 431 killed and wounded. Mexican casualties are unknown, but Scott captured over 3,000 prisoners. The road to Mexico City was now open.