Battle of Monterrey

In the Battle of Monterrey (September 21–24, 1846) during the Mexican–American War, General Pedro de Ampudia and the Mexican Army of the North was defeated by the Army of Occupation, a force of United States Regulars, Volunteers, and Texas Rangers under the command of General Zachary Taylor.

The hard-fought urban combat led to heavy casualties on both sides. The battle ended with both sides negotiating a two-month armistice and the Mexican forces being allowed to make an orderly evacuation in return for the surrender of the city.

Following the Battle of Resaca de la Palma, Taylor crossed the Rio Grande on 18 May, while in early June, Mariano Arista turned over command of what remained of his army, 2,638 men, to Francisco Mejia, who led them to Monterrey. On 8 June, United States Secretary of War William L. Marcy ordered Taylor to continue command of operations in northern Mexico, suggested taking Monterrey, and defined his objective to "dispose the enemy to desire an end to the war." On 8 August, Taylor established the headquarters for his Army of Occupation in Camargo, Tamaulipas and then in Cerralvo on 9 September with 6,640 men. Taylor resumed the march to Monterrey on 11 September, reaching Marin on 15 September and departing on 18 September

In early July, General Tomas Requena garrisoned Monterrey with 1,800 men, with the remnants of Arista's army and additional forces from Mexico City arriving by the end of August such that the Mexican forces totaled 7,303 men. General Pedro de Ampudia received orders from Antonio López de Santa Anna to retreat further to the city of Saltillo, where Ampudia was to establish a defensive line, but Ampudia disagreed, sensing glory if he could stop Taylor's advance. Ampudia's forces included reinforcements from Mexico City totaling 3,140 men: 1,080 men of the Garcia-Conde Brigade (Gen. Jose Garcia Conde) (Aguascalientes and Querétaro Battalions, two squadrons of the 3d Line Cavalry, three guns (3-8 lbs)), a thousand men of the Azpeitia Brigade (Col. Florencio Azpeitia) (3d Line, two squadrons of the Jalisco lancers, two squadrons of the Guanajuato Cavalry Regiment, six guns (8 and 12 lbs.) and an ambulance), 1,060 men of the Simeon Ramirez Brigade (Acting Gen. Ramirez) (3d and 4th Light, three guns (1-8 lbs, 2-12 lbs) and 3 howitzers 7" (Capt. P. Gutierrez and Comdte. A. Nieto)) and an artillery unit, the largely Irish-American volunteers called San Patricios (or the Saint Patrick's Battalion), in their first major engagement against U.S. forces.

Taylor's army, with the Texas Division leading under the command of Major General and Texas Governor James Pinckney Henderson, reached the plain in front of Monterrey at 9 am on the morning of 19 September, when they were fired upon by Col. José López Uraga's 4th Infantry guns, located at San Patricio Battery atop the citadel. Taylor ordered the army to camp at Bosque de San Domingo while engineers under the command of Major Joseph K. Mansfield reconnoitered.

Besides the citadel, Mexican strong points within the city included the "Black Fort" (Col. Jose Lopez Uraga, 3d & 4th Line and 9 guns – incl. "San Patricio" Battery); "the Tannery," La Teneria, (2d Ligero under Col. José M. Carrasco and part of the Querétaro Battalion, and 2 guns & 1 mountain howitzer – Lt (?) J. Espejo) El Fortín del Rincón del Diablo (Lt. Col. Calisto Bravo and 3 guns- Capt. Ignacio Joaquin del Arenal); La Purísima bridge and tete-de-pont (Activos of Aguascalientes under Col. Jose Ferro and the Querétaro under Comdte. José María Herrera 3 guns – Capt. P. Gutierez). West of the city atop Independencia stood Ft. Libertad ( 4 guns) and the Obispado (bishop's place) with the Activos of Mexico commanded by Lt. Col. Francisco de Berra and 3 guns and 1 howitzer, and atop Federacion was a redan(2 guns) and Fort Soldado. In reserve at la Plaza was the 3d Ligero under Lt. Col. Juan Castro and 1 gun – Lt. Agustín Espinosa.

General Zachary Taylor decided to attack western Monterrey using William J. Worth's Division in a giant north and west "hook" movement while simultaneously attacking with his main body from the east. Worth started at 2 pm on 20 September with Col. John Coffee Hays's Texas Mounted Riflemen Regiment screening the advance, but camped for the night three miles from the Saltillo road.

By 6 am on 21 September, Worth continued his advance, repulsing a Jalisco cavalry charge by Col. Juan Nájera, killing the latter and an advance guard consisting of General Manuel Romero's brigade and Lt. Col. Mariano Moret's Guanajuato Regiment. By 8:15 am, Worth had severed the Saltillo road from Monterrey and sent Capt. Charles F. Smith with 300 infantry and Texans, plus Capt. Dixon Miles's 7th Infantry and Persifor Smith's 2nd Brigade to take Federacion and Fort Soldado, which they quickly did.