Located in Plaza San Jacinto in San Angel, a suburb of Mexico City, a war memorial honors the San Patricios, which translates to St. Patrick’s Battalion. This battalion of Irish-born and Irish-American soldiers fought for Mexico during the Mexican-American War between 1846 and 1848.



There are a couple different reasons for the battalion’s defection to Mexico. One theory reasons that the Irish Americans felt an affinity with the invaded Mexico as England had invaded Ireland. Another theory suggests that anti-Catholic attitudes within the Protestant dominated U.S. army convinced them to fight with fellow Catholics in Mexico. A simpler explanation argues that the Mexicans offered them land and better pay.



The Mexican-American War brought many Irish far from their native land. Influenced by Manifest Destiny, the idea America should extend from coast to coast, President James K. Polk had encouraged American settlers to move to the recently annexed Texas, which many Mexicans still considered part of Texas. Polk sent American forces under Zachary Taylor to defend the area and when the Mexican army ambushed this force, Congress declared war on May 13, 1846. The American army won many battles in Mexico throughout 1846 and 1847. Mexicans continued guerilla warfare until 1848.



John Riley, 2nd lieutenant who had come from Galway, led the battalion to switch sides in 1846. The battalion included Germans, Scottish and American Catholics and they often entered battle under an emerald flag featuring the words “Erin Go Bragh.” Riley’s knowledge of artillery and infantry warfare helped the Mexican army, but the Americans defeated San Patricios at the Battle of Churubusco on August 20, 1847. Battle survivors were found guilty of treachery by military court martial and 48 were sentenced to death by hanging and others serve long prison sentences.



The soldiers of San Patricios were just a few of Irish-born soldiers fighting in the war. Michael G. Connaughton quoted military historian Brian McGinn in his article “Beneath an Emerald Green Flag: The Story of Irish Soldiers in Mexico,” “[Irish Americans] could argue, and convincingly, that the overwhelming majority of the 4,811 Irish-born soldiers who served in the U.S. army during the Mexican-American War did not desert. Even if all the San Patricios soldiers were Irish- and they were not- Irish-born deserters would represent less than four percent of Irish soldiers.” Thousands of Irish-born soldiers served America as their adopted country honorably and gave the ultimate sacrifice.



The Treaty of Guadalupe Hidalgo ended the Mexican-American War ended on February 2, 1848. The U.S. acquired Texas, New Mexico, and California, which increased the U.S.’s territory by one third.



Mexico remembers the soldiers of San Patricios as heroic martyrs and their sacrifices are still honored today. Dignities from the Mexican government and the Irish embassy attend a commemoration each year in the Plaza San Jacinto. Both the Mexican and the Irish national anthems are played and an honor guard of elite Mexican soldiers salutes the deceased.