The opening battles of the Mexican War had been won by the Americans with relative ease. Palo Alto saw the use of superior artillery decide the day. The improvised deployment of troops in small squads at Resaca de la Palma drove Mexican forces from terrain covered in thick underbrush won the day. Monterrey was different. The terrain, this time, would be a city, the first urban warfare faced by the Army since the American Revolution.
“The city has got to be carried and as there are no guns in our train of sufficient caliber to batter, the bayonet will probably have to do the work. It is a perilous undertaking and we must anticipate immense slaughter…”
CPT Philip N. Barbour, 3rd Infantry
On the 21 September 1846, the 3rd Infantry, 262 men strong, was part of the first wave to attack Monterrey. Enemy artillery was stationed at street intersections, and the narrow streets were bounded on each side with buildings filled with infantry. In penetrating the first line of defense of the walled city, the Regiment found itself drawn into a situation in which the limited space to maneuver made it difficult for American units to support each other.
“As we advanced, battery No.1 opened upon us. An enfilading fire was opened upon us from the citadel. The line steadily but rapidly advanced, regardless of all fire; important work was to be performed, and we had made up our minds to carry all before us at the point of a bayonet. We rushed into the streets. From all its embrasures, from every house, from every yard, showers of balls were hurled upon us. Major Barbour was the first officer who was shot down.”
CPT William S. Henry, 3rd Infantry
The losses that ensued reflect the nature of the combat. Over forty enlisted men were casualties; five officers, including the three senior officers, were killed and five wounded. The unit took its objective and held its ground until a lack of ammunition made withdrawal a necessity. The Regiment remained under Mexican artillery fire during the night and into the morning, when the city fell to the American army. The bitter house-to-house defense of the city by the Mexican troops made it the most costly single day in the history of the 3rd Infantry until Gettysburg.
“We were then ordered to retreat out of town to form another charge…We came out in parties from 30 to 100. As soon as we got out of town we saw the Lancers coming down in great numbers at a full charge. They gained on us rapidly…The slow runners were soon overtaken and killed. Captain Fields was among the first victims. They killed without mercy. We then formed and went in again and fought two hours more…”
PVT Barna Upton, Company C, 3rd Infantry
In 1920, the Regiment selected the anniversary of Monterrey to serve as Organization Day to remember the fierce fighting and the men lost during the Monterrey campaign.
The Regiment entered the battle with six companies and an effective strength of 14 officers, 40 non-commissioned officers, 7 musicians and 201 privates for a total of 262 officers and men. Losses totaled 52 (20%): 6 Officers KIA or DOW, 1 Officer WIA, 15 NCOs and Privates KIA or DOW, 29 NCOs and Privates WIA, 1 Musician WIA. Included among the officers killed were the Regimental Field Commander and the Regimental Adjutant.