On April 12, Lieutenant
Pierre G. T. Beauregard, of the
United States Army Corps of Engineers, determined that possession of Atalaya Hill would enable the Mexican position to be turned. The
Personal Memoirs of Ulysses S. Grant observe that, in order to determine whether a flanking movement was possible, "reconnaissances were sent out to find, or to make, a road by which the rear of the enemy's works might be reached without a front attack." These reconnaissances were made under the supervision of Captain
Robert E. Lee and other officers, "all of whom attained rank and fame." Grant continues that it was the roadways constructed by the engineers which achieved victory: Twiggs' division took the hill on April 17, advancing up the slopes to El Telegrafo. Santa Anna reinforced El Telegrafo with Brigadier General Ciriaco Vasquez's 2d Light, 4th, and 11th Infantry. Captain
Edward J. Steptoe set up his battery on Atalaya Hill and Major James C. Burnham set up a
howitzer across the river. At 7:00 am on April 18, Twiggs directed
William S. Harney's brigade to move against the front of El Telegrafo while
Bennett C. Riley attacked from the rear. The combination easily took the hill, killing General Vasquez, and Captain
John B. Magruder turned the Mexican guns on the retreating Mexicans. Simultaneously,
James Shields' brigade attacked the Mexican camp and took possession of the Jalapa road. Once they realized they were surrounded, the Mexican commanders on the three hills surrendered and by 10:00 am, the remaining Mexican forces fled. 199 officers and 2,837 enlisted men were taken prisoner by the Americans. ==Aftermath==