The men of the Saint Patrick’s Batallion, also known as Los Patricios, were a group of soldiers who defected from the U.S. Army to fight for Mexico during the Mexican-American War. Known for their bravery and valor, the men — most, but not all, Irish — fought with distinction and are honored today in both Mexico and Ireland.
John Riley, Irishman, Catholic and rifleman par excellence
John Riley was born in County Galway, in western Ireland, sometime between 1805 and 1818. At the time, Ireland was part of the United Kingdom and deeply poor, even before the great famine of 1845. As with many Irishmen of the era, Riley made his way to Canada and eventually to Michigan in the United States. He was an excellent artilleryman and joined the U.S. Army, where he was stationed at Fort Mackinac to train West Point cadets.
Riley became disillusioned with the United States. There was a lot of anti-immigrant and anti-Catholic sentiment, talk of western expansionism and war with Mexico. Immigrants in the army were treated very harshly. He was eventually sent to Texas where he promptly deserted the U.S. Army on April 12, 1846, slipping across the border to Mexico and offering his services to the Mexican army.
James K. Polk and Manifest Destiny
President James K. Polk believed in Manifest Destiny, an ideology that embraced the idea that white Americans were divinely ordained to settle the entire continent of North America from the Atlantic Ocean to the Pacific. Not all Americans, especially Northerners and Irish immigrants, agreed with Manifest Destiny, and they did not want a war with Mexico. Many felt that his plans were merely an attempt to expand U.S. territory to increase the number of slave states.
When Polk sent troops to the disputed territory in Texas, his critics became more outspoken believing this would lead to war with Mexico. Then-Congressman Abraham Lincoln argued that “President James Polk sent American military forces into the disputed territory to intentionally provoke a military response from Mexico, who was just defending their homeland from an invasion.”
Why did Irish Immigrants defect to Mexico?
Riley was welcomed by the Mexican army. When war broke out, he was promoted to Lieutenant and given permission to organize a unit comprised of Irishmen who would desert the U.S. Army and join the Mexican Army. Riley quickly persuaded 48 other Irish immigrants to desert and join his unit in the Mexican Army. Most of them were also traumatized by the Irish Potato Famine and sectarian British policies that devalued Irish life and privileged Protestants over Catholics back at home. Many also experienced anti-Catholic bigotry in the U.S. Army. They were seen as lazy, ignorant and foolish, so they were given the most dangerous jobs.
Mexico sees an opportunity
Seeing an opportunity, Mexico began actively recruiting immigrants in the U.S. Army — offering promotions, land ownership, pay increases, and religious freedom. Riley’s unit of Irishmen grew to 200. They were joined by immigrants from Germany, Poland, and France who were also disenchanted by the widespread bigotry against Catholics in the United States and felt a fierce loyalty to Catholicism. The promise of land and money also attracted escaped slaves and free Blacks who saw Mexico — which had outlawed slavery — as a freer country than the United States.
Riley named their unit the St. Patrick’s Battalion — known in Mexico as the San Patricios — in honor of Ireland’s patron saint. The men recruited were all skilled artillerymen and were assigned to Riley’s battalion. They marched under a green banner with an image of St. Patrick on one side and a harp and emblem of Mexico on the other. Their ranks swelled from 200 to 700 and they were considered some of the most fearless and skilled soldiers in the Mexican Army.
The San Patricios become heroes
The San Patricios demonstrated their bravery in Northern Mexico and played a major role in the Battle of Buena Vista in Coahuila in February 1847. When defeat was imminent in the battle, the St. Patrick’s Battalion provided cover for the Mexican forces’ safe retreat. Several were awarded the Cross of Honor medal for their heroism, including Riley who was promoted to captain.
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When the Americans opened another front further south, the San Patricios accompanied General Antonio López de Santa Anna to Mexico City where they made a name for themselves at the Battle of Churubusco, as Mexican forces tried in vain to defend the castle from encroaching U.S. forces.
Most of the defenders were killed or captured in the defeat. John Riley was among the 85 San Patricios captured during the battle. They were court-martialed, most were found guilty of desertion and 50 were condemned to be executed by hanging.
Riley was the highest profile San Patricio but was spared hanging because it was established that he had deserted before the war began — a less serious offense — but was punished harshly. His head was shaved, he was given more than 50 lashes and was branded on both cheeks with a “D” for deserter. He was then thrown into a dungeon for the remainder of the war.
The execution of the San Patricios was the largest ever ordered by the U.S. military. Col. William Selby Harney — a man known for his cruelty and brutality — was ordered to carry out the hanging. He brutally hung all 50 men at the same time facing Chapultepec Castle so they could watch the flag of the United States being raised over Chapultepec before being executed. The flag was raised at 9:30 am on September 13, 1847, and the men were executed. Harney, answering to criticism, said, “I was ordered to have them hanged and I had no orders to unhang them.”
No one knows what happened to John Riley, but he is presumed to have died in 1850.
The Treaty of Guadalupe Hidalgo was signed on February 2, 1848, officially ending the war. The United States paid Mexico US $18 million and received almost half of the Mexican territory including California, Nevada, Utah, New Mexico, parts of Oklahoma, Kansas, Wyoming, and most of Arizona and Colorado.
In his memoirs, shortly before his death, Ulysses S. Grant would describe the Mexican-American War as “the most unjust war ever waged by a stronger nation against a weaker nation. It was an instance of a republic following the bad example of European monarchies in not considering justice in their desire to acquire additional territories.”
The San Patricios are heroes in both Ireland and Mexico
John Riley is considered a great hero in both Ireland and Mexico. The San Patricios themselves have earned a place of honor in Mexican history. Statues of Riley have been erected and plaques honoring the San Patricios placed in both countries. Streets have been named for them and there are annual tributes to honor them.
On the 150th anniversary of the Battalion’s creation Ireland and Mexico jointly issued identical postage stamps with flags of both countries honoring their heroism and legacy. At the same time, Mexico inscribed gold-lettered words honoring the Battalion on the Wall of Honor located in the Chamber of Deputies of the Mexican Congress.
The Irish band The Chieftains recorded a song to honor the San Patricios, “March to Battle,” narrated by Liam Neeson.
The U.S. military denied the existence of the St. Patrick’s Battalion for 60 years until a 1915 congressional inquiry revealed a coverup of their history.
Sheryl Losser is a former public relations executive, researcher, writer and editor. She has been writing professionally for 35 years. She moved to Mazatlán in 2021 and works part-time doing freelance writing. She can be reached at AuthorSherylLosser@gmail.
