Formation and early engagements Present in the Mexican Army for the battles of
Palo Alto and
Resaca de la Palma were the
Legión de Extranjeros (Legion of Foreigners); the men who would later make up the core of the Saint Patrick's battalion. Meanwhile, deserters were abandoning General Taylor's army on the
Rio Grande. Riley and "a company of 48 Irishmen" manned Mexican artillery at the
Siege of Fort Texas, which took place concurrently to the two other battles.
Martin Tritschler,
German Mexican and a Captain at the
Battle of Cerro Gordo, is attributed with convincing a large number of German soldiers to defect from the U.S. occupying forces in
Puebla, Puebla. The first major engagement of the Saint Patrick's Battalion, as a recognised Mexican unit, was as an
artillery battery in the
Battle of Monterrey of 21 September 1846. Popularly they were called
Los Colorados by the Mexicans because of their ruddy, sun-burnt complexions and red hair color. They were commanded by
John Riley, an Irishman who had previously served in the
British Army as a
non-commissioned officer and possibly arrived in Canada in 1843 whilst serving in his British unit (the assertion that Riley was a
sergeant in the
66th (Berkshire) Regiment of Foot is known to be inaccurate). Riley went on to join the U.S. Army in Michigan in September 1845. He deserted in Matamoros in April 1846. Upon meeting Mexican forces he was initially given the
Officer rank of
Lieutenant by
General Pedro de Ampudia. At the battle of Monterrey the proved their artillery skills by causing the deaths of many American soldiers, and they are credited with defeating two to three separate assaults into the heart of the city. Among their targets were companies led by such officers as
Braxton Bragg, many of whose soldiers would end up in their own ranks later in the war. Their tenacity, however, did not affect the Mexican commanders' decision to capitulate and abandon the position. Following the engagement at
Monterrey, the grew in number, by some estimates reaching an enlistment of over 700 men. Forces re-assembled at
San Luis Potosí and they had their distinct green silk flag embroidered there.
Buena Vista They then marched northward after joining a larger force commanded by
Antonio López de Santa Anna sent from Mexico City, the "liberating army of the North". At the
Battle of Buena Vista (known as the battle of Angostura in Mexico) in
Coahuila on 23 February, the Patricios became engaged with U.S. forces. They were assigned the three heaviest—18 and 24 pound—
cannons the Mexican army possessed, which were positioned on high ground overlooking the battlefield, at the base of a hillside (just below what is now a gravel mine). They were later described as "a strong Mexican battery ... moved ... by dint of extraordinary exertions ... [that] commanded the entire plateau". They started the battle supporting Mexican infantry by firing on U.S. lines as the Mexicans advanced on them, then later decimating an artillery battery directly opposite them on the battlefield (Washington's 4th Artillery, D Battery). A small number of were dispatched with a
division commanded by
Manuel Lombardini with the express purpose of capturing the 4th's cannons once the crews had been dealt with. As the division got close enough they charged the artillery battery, bayoneting whoever remained and
routing the rest, leaving the attached free to haul away two six-pound cannons. These cannons would later be used by Mexican forces at the
Battle of Contreras. In frustration U.S. Commander
Zachary Taylor, referring to the Saint Patrick's Battalion, ordered a
squadron of the
1st Dragoons to "take that damned battery". In this task they failed, and, badly bloodied, were forced to retreat. At about 1 p.m. the covered a Mexican retreat as a disordered mass of infantry sought refuge during a lull in the fighting. The rode out the day in a costly artillery duel with several American batteries, which killed or injured roughly one third of them. General Francisco Mejia's Battle Report for Buena Vista described the ' as "worthy of the most consummate praise because the men fought with daring bravery." Several Irishmen were awarded the
War Cross by the Mexican government for their conduct in that battle, and many received field promotions.
Re-organization and final battles Despite their excellent performance in a number of engagements as artillery, the much-reduced were ordered to muster a larger
infantry battalion, as well as a cavalry unit, in mid-1847 by personal order of Santa Anna. It was renamed the
Foreign Legion of Patricios and consisted of volunteers from many European countries, commanded by Col. Francisco R. Moreno, with Riley in charge of 1st
company and Santiago O'Leary heading up the second. Desertion handbills were produced, specially targeting Catholic Irish, French and German immigrants in the invading U.S. army and stating that "You must not fight against a religious people, nor should you be seen in the ranks of those who proclaim slavery of mankind as a constitutive principle ... liberty is not on the part of those who desire to be lords of the world, robbing properties and territories which do not belong to them and shedding so much blood in order to accomplish their views, views in open war to the principles of our holy religion". 's monastery at the height of the 1847
Battle of Churubusco, painted by James Walker The
Battle of Churubusco (20 August 1847) took place about four months after the defeat at Cerro Gordo. Gen. Santa Anna gave a verbal order to "preserve the point at all risk". The San Patricio Companies initially met the attackers outside the walls of the convent at a
tête-de-pont, which was about from a fortified convent. A battery of three to five heavy cannons were used from this position to hold off the American advance along with support from
Los Independencia Batallón and
Los Bravos Batallón. The Americans were under the command of
Col. William Hoffman. Several U.S. charges towards the bridgehead were thrown off, with the companies serving as an example to the supporting battalions. Unlike the , most of whom were veterans (many having served in the armies of the United Kingdom and various German states), the supporting Mexican battalions were simply
militia (the term 'National Guard' is also used) who had been untested by battle. A lack of ammunition led the Mexican soldiers in the trenches between the bridgehead and the convent to disband; without ammunition, they had no way to fight back. Santa Anna had ordered half of these soldiers to a different part of the battlefield. When the requested ammunition wagon finally arrived, the 9 ½
drachm cartridges were compatible with none but the San Patricio Companies "
Brown Bess" muskets, and they made up only a fraction of the defending forces. Further hampering Mexican efforts, a stray spark from an artillery piece firing
grapeshot at the on-coming U.S. troops caused the just-arrived ammunition to explode and set fire to several men, including Captain O'Leary and Gen. Anaya. A
withdrawal behind the walls of the
convento de Churubusco was called when the threat of being outflanked proved too great. The used this battle as a chance to settle old scores with U.S. troops: "The large number of officers killed in the affair was ... ascribed to them, as for the gratification of their revenge they aimed at no other objects during the engagement". At some point during the fighting for the convent, two American officers led fifteen men against a point in the Mexican defenses, and mistook members for friendly U.S. army troops; the opened fire on them, killing or wounding all but one of the group. Though hopelessly outnumbered and under-equipped, the defenders repelled the attacking U.S. forces with heavy losses until their ammunition ran out and a Mexican officer raised the white flag of surrender. Officer Patrick Dalton of the tore the white flag down, prompting Gen.
Pedro Anaya to order his men to fight on, with their bare hands if necessary. American Private Ballentine reported that when the Mexicans attempted to raise the
white flag two more times, members of the shot and killed them. After brutal
close-quarters fighting with
bayonets and
sabers through the halls and rooms inside the convent, U.S. Army
Captain James M. Smith suggested a surrender after raising his white handkerchief. Following the U.S. victory, the Americans "ventilat[ed] their vocabulary of Saxon expletives, not very "courteously", on Riley and his beautiful disciples of St. Patrick." Gen. Anaya stated in his written battle report that 35 were killed, 85 taken prisoner (including a wounded John Riley, Captain O'Leary, and Anaya); about 85 escaped with retreating Mexican forces. Some 60% of the were killed or captured in the engagement. The survivors were reformed before the
Battle of Mexico City some two weeks later and were stationed at
Querétaro where the Mexican government had decamped, with some 50 members serving as a body-guard for the commander-in-chief. The battalion were caught up in the infighting and politicking of Mexico at the time, and were under the patronage of a faction that favored suing for ending of the conflict peacefully. New units were later made up of the free survivors of the battle of Churubusco and a roughly equal number of fresh deserters from the U.S. Army. Following the war, the Mexican Government insisted in a clause of the
Treaty of Guadalupe Hidalgo that the remaining prisoners held by the Americans were to be left in Mexico, and Major General
William Orlando Butler issued General Orders 116 on 1 June 1848 stating that; "The prisoners confined at the Citadel, known as the prisoners, will be immediately discharged"—
Rogue's March was played upon their release. The Saint Patrick's Battalion continued to function as two infantry companies under the command of John Riley, with one unit tasked with sentry duty in Mexico City and the other was stationed in the suburbs of Guadalupe Hidalgo. The were officially mustered out of Mexican military service in 1848; some members were alleged to have been involved in an abortive
military coup, while historians have said the group was disbanded because of Mexican budget cuts. ==Aftermath of Churubusco==