The Saint Patrick's Battalion (Spanish: Batallón de San Patricio) was a unit of several hundred immigrants and expatriates of European descent that fought as part of the Mexican Army against the United States in the Mexican-American War of 1846 to 1848. Many of the battalion's members deserted or defected from the U.S. Army. Primarily made up of Irish and German immigrants, the battalion also included Canadians, English, French, Italians, Poles, Scots, Spaniards, native Mexicans and Swiss, mainly Roman Catholics.[1] Disfranchised Americans were also in the ranks, including African Americans who had been slaves in the American South.[2] Coming from many different national and ethnic backgrounds, all members of the battalion were granted Mexican citizenship upon entering Mexican service — none of the members, except for the few Americans, had ever been U.S. citizens.
U.S. regiments members of the battalion are known to have deserted from include the 1st Artillery, the 2nd Artillery, the 3rd Artillery, the 4th Artillery, the 2nd Dragoons, the 2nd Infantry, the 3rd Infantry, the 4th Infantry, the 5th Infantry, the 6th Infantry, the 7th Infantry, and the 8th Infantry.[3]
The battalion served as artillery for much of the war, and despite later being formally designated as infantry, it still retained artillery pieces throughout the conflict. In many ways the battalion acted as the sole Mexican counter-balance to U.S. Horse artillery.
For Americans of the generation who fought the Mexican-American War, the "San Patricios" were considered traitors.[4] For Mexicans of that generation, and generations to come, the San Patricios were heroes who came to the aid of fellow Catholics in need.[5][6]
The great majority of these men were recent Irish diaspora from northeastern US ports, escaping extremely poor economic conditions in Ireland, which at the time was part of the United Kingdom of Great Britain and Ireland. In this respect, it is consequent that throughout the Saint Patrick's battalion's active years the Irish Potato Famine was taking place. Irishmen and other immigrants were often recruited directly into military service shortly or sometimes immediately on arrival. Others were conscripted on their way south by General Zachary Taylor,[7] with promises of salaries and land after the war.
Commemorative plaque at San Jacinto plaza in the district of San Ángel, Mexico City
Mexican author José Raúl Conseco writes that many Irish lived in northern Texas, and were forced to move south due to regional insecurity. Early in the war they helped Taylor attack the fort and supply depot in St. Isabel, now the city of Port Isabel, Texas.
Many theories exist on motivations for desertion, including cultural alienation,[8] mistreatment of immigrant conscripts by other nativist soldiers and senior officers,[9] not being allowed to attend Sunday Mass or to practice their religion freely, the incentive of land in Mexico (starting at 320 acres[10]) and witnessing the conduct of U.S. troops following battle victories.
One school of thought is that based on the evidence of the number of Irish Catholics in the Battalion, the letters of Riley, and the field entries of senior officers the primary motivations seem to have been shared religion and sympathy for the Mexican cause, likely based on similarities between the situations in Mexico and Ireland.[11][12] Another is that the members of the Saint Patrick's Battalion were not happy with their unfair treatment, and switched sides for the promise of better conditions, higher wages and land grants.[13]
Relevant historical considerations include Irish expatriates' long tradition of serving in Catholic countries' military forces dating back to the Flight of the Wild Geese in the 17th century, and more recent history detailing of the role played by Irish soldiers in South American wars of independence.[c]
