The Irish Heroes of Mexico

Batallón de San Patricio: the Irish Heroes of Mexico

Paper appears courtesy of Martín Paredes – 


On September 12, 1997, Mexican President Ernesto Zedillo held a ceremony in Mexico City in honor of the 150th anniversary of the San Patricio Battalion. Representing Ireland, Ambassador Sean O’Huighinn was also present.1 Although at least two historical accounts have been written about the Mexican Irish soldiers, for the most part, the general population of the United  States is not aware of the Irish who fought for Mexico during the Mexican-American War. Few, outside of Mexico, have ever heard of the Irish soldiers who defected from the American lines and bravely fought defending Mexico from the American invasion. This is the story of the Batallón de San Patricio. For Mexicans, the men of the San Patricio Battalion will forever be enshrined in Mexico’s hall of honor.


The Mexican-American War of 1846-1848
The Mexican-American War lasted for two years, from 1846 until 1848. It resulted in 25,000 Mexican soldiers dead or wounded, according to the archives of the Mexico’s Secretariat of National Defense. Mexico also lost about 40% of its territory. The Americans suffered 17,423 dead or wounded and had over 9,000 soldiers go AWOL, according to American records. The war started as a result of the declaration of independence by the State of Texas in 1836 and the subsequent annexation of Texas into The United States in 1846. On May 11, 1846, U.S. President James K. Polk asked and received approval by Congress to declare war on Mexico. On May 13, 1846 the United States officially declared war.2 Although the perceived pretext for war was the Mexican insistence that Texas was not free to join the American Union, historians have generally accepted that the war was about the expansion of the American empire through Manifest Destiny.
As America prepared for war, thousands of European immigrants hit the American shores. Among these were the Irish who were fleeing the Great Hunger of 1845. With the offer of free acres of land and three months of advanced pay, many enlisted in the American army.


Unprecedented American Desertions
John Miller, in his book; “Shamrock and Sword” writes that the desertion rate for American forces was the highest during this conflict as compared to other wars. According to Miller, the rate was 8.3%, compared to 5.3% for World War II and 4.1% for the Vietnam War. All the other wars in which Americans participated came in at less then 2%.4 Peter Stevens, in his book; “The Rogue’s March: The Saint Patrick’s Battalion” wrote that no U.S. Army has ever encountered the problems of desertion that plagued Generals Zachary Taylor and Winfred Scott. He adds that of nearly 40,000 regulars, 5,331 deserted.
The Reasons for Deserting and Joining the Opposing Army
Very few historians have written about the San Patricios. There are two reasons for this, on the American side the war was unpopular and was ultimately over shadowed by the American Civil War. Besides the debate within the United States about the war, the high desertion rates from the American lines made the discussion of the war taboo within the American military. On the Mexican side, the loss of a substantial part of its territory and the ongoing civil strife within Mexico has left a lack of historical record for the war. Two authors have written two books about the Saint Patrick soldiers. They are Peter F. Stevens who wrote “The Rogue’s March: John Riley and the St. Patrick’s Battalion” and Robert Ryal Miller, author of “Shamrock and Sword, The Saint Patrick’s Battalion.”

Although they both discuss the high desertion rate of the American soldiers, they seem to be trying to minimize the actions of the American Army before the war started. Historians on both sides of the border have acknowledged that the Americans were intent on instigating war with Mexico through unprovoked crimes; such as rapes and plunder and especially the desecration of Catholic Churches in Texas, the disputed territory. Also, many immigrants in the American army not only felt discriminated upon 6 by their fellow soldiers but also could not accept the American provocation for war. They began to dissert and cross the river to join the Mexican army in defense of Mexico. From the moment of the first battle at Palo Alto on May 8, many of the deserters battled their former comrades. German Christopher Friedrich Wilhelm Zeh, who coincidently did not like Mexicans, wrote in his memoirs that the US Army was a multicultural group where one of every thousand was an immigrant. 7 By his own admission, Zeh was an educated immigrant who considered himself an aristocrat. Although the American Army was composed of recent immigrants, discrimination permeated through the ranks. Catholic prejudice 8 and harsh treatment by Anglo-American superiors and the use of extreme disciplinary measures such as flogging added to the reasons for the desertions from Taylor’s ranks.9 “Potato heads” as the Irish were commonly called were particularly singled out for harsh treatment. 10 Under these conditions the immigrants had no difficulty abandoning their army and joining the Mexican lines in defense of Mexico. Mexico was especially active in recruiting the deserters.


Mexican Recruitment Efforts
Mexico has historically recruited foreigners to fight in its ranks since its War of Independence. Although authors Miller and Stevens seem to make much of Mexico’s active recruitment of American soldiers into the Mexican lines, for Mexico this was not something new, it was part of its war tactics. Foreigners have continuously been welcomed into the Mexican military ranks. By the time the U.S.-Mexican War started, 16 foreigners had reached the rank of general in the Mexican army with many others serving in other capacities.

Throughout the war, Mexico actively recruited American soldiers to defect their lines and join the Mexican army. The German immigrant Zeh, serving in the US Army acknowledges in his memoirs that the Mexicans routinely passed out pamphlets directed at the American immigrant soldiers printed in German, English and French. According to Zeh, the pamphlets read; “We live in peace and friendship with nations you come from. Why do you want to fight against us? Come to us! We will welcome you as friends with open arms, take care of your needs, we offer you more than the Yankees can provide, due to their brazenness, we (sic) have been forced into this war. Join us and fight with us for our rights and for our sacred religion against this infidel enemy”. Zeh adds, “Several hundred Irishmen, stirred up by religious fanaticism, went over to the enemy, thanks to this piece of paper.”

To the Irish, the call for defending the motherland against invaders resonated among them as they remembered the Penal Times in their history. [1] They embraced the Mexican position that simple farmers were being attacked for their land and decided to join the Mexican ranks.


El Batallón de San Patricio
In October of 1846, after an additional 50 or so, American soldiers had deserted the American ranks, bringing the total number of deserters to about 100, 14 Santa Anna, using war powers bestowed upon him by the Mexican Congress directed that two infantry companies be formed. 15 The two companies would form the Batallón de San Patricio. Each company consisted of one captain, one lieutenant, two second lieutenants, one first sergeant, four sergeants, nine corporals, four cornets and eight soldiers. According to a dissertation by author Dennis Wynn, the battalionwas formed in October of 1846 as a separate unit. 16 Additionally, according to Mexican army payroll records for November 1846, “Voluntarios Irlandeses” were receiving pay from the Mexican government.

Although the San Patricio Battalion was made up predominantly of Irish immigrants, other European nationalities also comprised the element. 18 Of the 175 members of the San Patricio Battalion, 40 were from Ireland, 22 from the United States, 14 from the German States and the rest from other countries.


The Green Silk Banner
Although not in common use in smaller units, Santa Anna allowed the San Patricios to fly a war banner during the war. The green banner, made by peasants according to Mexican publications, had on one side a golden harp surmounted by the Mexican Coat of Arms with a scroll on which was painted “Libertad por la Republica Mexicana”. Under the harp was the motto of “Erin go Bragh!” On the other side was a figure, made to represent St. Patrick, in his left hand a key and in his right a crook or staff resting upon a serpent. Underneath was added “San Patricio”. 20 No known existence of the flag exists today, although a couple of reproductions have been made.


John Riley
John Riley of K Company, 5th Infantry 21 deserted his American post and joined the Mexican ranks on April 12, 1846 22 prior to the US declaring war on Mexico. It is important to note that Riley defected the American ranks prior to the actual declaration of war, thus it was peace time when he abandoned the US Army. He is generally credited with organizing the Irish Battalion. Part of the confusion, over whether Riley organized the battalion is caused by the different spellings of his name found in official government records. John Riley, himself signed his name as Riley, other times as Riely, Reilly, or O’Riley in his correspondence to others. Mexican government records list him as Juan Reyle, Reley, Reely or Reily. His enlistment record for the U.S. Army lists him as Reilly.

On September 2, 1845, Riley enlisted for a five-year term at Fort Mackinac. He left for the Texas border two days later. During the last three weeks in March of 1846, Riley, under Taylor’s Army, setup camp in Texas, just across the river from Matamoros. On April 12, 1846, Riley obtained a pass from Captain Merrill to attend a Catholic Mass, deserted and joined the Mexican Army.

According to the records of the period, Sergeant John Riley’s ability was such that he was in line for a lieutenant’s commission although rising through the ranks during this period was difficult at best. 25 This discredits some of the misinformation put out by some publications of the period that attempted to suggest that Riley was a malcontent soldier. Although, some historians have argued that Riley did not actually form the San Patricio Battalion, the plaque in Mexico City commemorating their contribution to the war gives credit to Riley for the formation of the battalion. 26 By most general accounts, The San Patricios fought bravely throughout the war. The Battle of Buena Vista and Churubusco is where the battalion left its most notable war marks.
The Battle of Buena Vista

One of the most “vicious” battles of the war was the Battle of Buena Vista 27 fought on February 22 and 23 of 1847, near Saltillo. In this battle 4,759 Americans engaged about 15,000 Mexicans. Rather than a battle, it was a serious of fights with few positions changing hands; consequently it was at first difficult to tell who had won. 28 General Francisco Mejia’s Buena Vista Battle Report lauded the San Patricios’ “as worthy of the most consummate praise because the men fought with daring bravery.”


The Battle of Churubusco
On August 19 and 20 of 1847, Mexico suffered two devastating defeats, the second of which saw the destruction of the San Patricios as a unit in this war. 30 Of the original 120 San Patricios, 35 were killed in action and 85 were captured by American forces. 31 It is probable that most of the 40 unaccounted for Irish soldiers continued to fight in other elements of the Mexican Army until the end of the war. The thirty-five San Patricios’ killed in action included two second lieutenants, 4 sergeants, 6 corporals and 23 privates. 32 American losses in this battle were, 137 killed, 879 wounded and 40 were missing.

After the battle, the captured San Patricios were tried for desertion during war time and all were found guilty and sentenced to death by hanging. Hanging was reserved for traitors. 34 According to President Zedillo’s speech honoring the memory of the Irish soldiers, more than 60 San Patricios were hanged, while ten were whipped and branded with the letter “D”. 35 Miller, on the other hand, reports in his book that under General Scott’s, General Orders 281 and 283, issued in the second week of September 1847, Scott upheld the capital punishment for 50 of the soldiers, pardoned five and reduced the sentences for the other fifteen. John Riley was included in the last fifteen because he had deserted during peace time and therefore could not receive the death penalty. 36 Riley had deserted prior to the official declaration of war.

Under orders of Winfield Scott, the last of the 50 San Patricios were hanged facing Chapultepec Castle precisely at the time the American flag was raised after the American victory during that battle. 37 The mass executions left a deep impression on the Mexican population. Rioting broke out in Toluca after the news reported that the executions had taken place. Mexicans intent on seeking revenge threatened to kill American prisoners but were prevented from doing so by the Mexican authorities. 38 From the Mexican point of view, the San Patricios should have been treated as prisoners of war, not criminals.

Instead of hanging, Scott ordered that the 15 San Patricios spared the death penalty, be instead branded with a two inch letter “D” for desertion with hot-iron on the right cheek and receive 50 lashes. It is unclear why three of the men were instead branded on the hip, rather than the face. These three were made to wear an eight pound iron collar with 3 one-foot long prongs each. 39 Scott also ordered that the San Patricios be imprisoned until the American army left Mexico. Upon being mustered out, Scott ordered that the men’s heads be shaved and drummed out of the Army. Although Scott intended to return the San Patricio men back to the United States at the conclusion of the war, the Mexican government prevailed in keeping them in Mexico.

The Mexican Government had called the punishments an act of barbarism, “improper in a civilized age.” 40 Under the terms of the Treaty of Guadalupe Hidalgo, the San Patricio prisoners were to be left in Mexico. Mexico had insisted on this clause in the treaty during the negotiations. Maj. Gen. Butler issued General Orders 116 on June 1, 1848. In the last paragraph of that order, Butler ordered that; “The prisoners confined at the Citadel, known as the San Patricio prisoners, will be immediately discharged.” After the officer in charge of the Citadel read the orders, the 16 prisoners, including John Riley had their heads shaved, the buttons of their uniforms stripped off and marched out of the fortress while the bugler played “Rogue’s March”. 41 John Riley, instead of being branded once, was branded twice according to some of the reports of the time. The reports indicate that the double branding may have been a result of the first “D” being applied backwards, either intentionally or under orders. The second “D” was then applied correctly.


The Aftermath
It can be argued that the defense of your homeland is a duty all citizens must obey when an invading army threatens to destroy your country. Many heroes have emerged from the defense of their nations. No truer hero exists than those who give their lives for their adopted nation. Authors Miller and Stevens have made central to their position that the San Patricios deserved what punishment they received by the fact that they had deserted. They have pointed to the records of the Court Martial’s, provided by the American government, where the defense for some of the San Patricios was “drunkenness”. Thirty-seven had pleaded not guilty and twentyseven had pleaded drunkenness. Both authors seem to imply that the San Patricios did not abandon the American lines for religious or discrimination reasons because none relied on religion or maltreatment as a defense.

Author, Wynn points out in his dissertation the futility of offering abuse or religion as a defense under the Articles of War during that time. Wynn goes on to point out that because of the trouble the American army had in keeping its soldiers in their ranks, they had instituted a general order whereby drunken AWOL soldiers were allowed back into their units with minor punishment. 42 The San Patricios’ probably chose to mount a defense against the hangmen’s noose the best way possible under the conditions of the time. Knowing the futility of maltreatment as a defense they chose drunkenness.

Part of the reason for the lack of more concrete information regarding the San Patricios and the distortion of their reasons for disserting the American army may lie in that the whole affair was an embarrassment to the United States. Continued Catholic persecution in the United States after the war may have also contributed to the distorted record. “Some newspapers in San Francisco cite that affair to prove that Catholics are disloyal,” wrote a private citizen in a letter to the Assistant Adjutant General in 1896 requesting information on the San Patricios.

Because of sentiments against Catholicism and the harsh treatment by American forces of the San Patricios, the American Army seemed reluctant to discuss the affair publically. In 1915, the American War Department was finally forced to acknowledge the existence of the San Patricios and their treatment of them at the end of the war. Ordered by Congress in 1917 to turn over the records to the National Archives the army complied. The documents detailed one of the most embarrassing episodes for the American Army. 44 For the San Patricios, their story could finally be told truthfully for all to know what was true in their hearts.

After leaving prison, the remaining San Patricios rejoined the Mexican Army and continued to function as a unit for almost a year after the Americans left Mexico. 45 Riley was made commander of the two infantry companies with the brevet rank of Lieutenant Colonel, (2) although he was actually a Captain. One unit was tasked with sentry duty in Mexico City while the other was stationed in the suburbs of Guadalupe Hidalgo. 46 By late 1850, 20 of the original San Patricios left Mexico and returned to Ireland under the agreement Mexico had made with them when they enlisted to help them return should they choose to do so. 47 Riley was not among them.
Juan Reley
Although the two books, “The Rogue’s March: John Riley” and “Shamrock and Sword” erroneously states that John Riley disappeared into history, John Riley died on the last days of August 1850 and was buried in Veracruz under the name “Juan Reley”, the name under which he had enrolled into the Mexican Army. 48 Miller, in his book, “Shamrock and Sword” acknowledged that Riley mustered out of the Mexican army in 1850 at Veracruz but speculated that Riley had left on a ship bound for Ireland.


Remembering the Irish Soldiers in Mexico
Mexicans celebrate the Irish soldiers on two days, September 12 in honor of the anniversary of the first executions and on March 17, St. Patrick’s Day. Numerous street names across the country honor their contribution to the Mexican cause. In front of the Convent of Santa María in Churubusco the street is named “Mártires Irlandeses”, or Irish Martyrs.


The Mexican government has officially recognized the contribution of the San Patricios through official acts of government. In 1997, President Zedillo held a ceremony in honor of the 150th anniversary of their executions along with Ireland’s ambassador. 51 On Thursday, October 28, 2002 the LVII Mexican Congress held a ceremony where the inscription “Defensores de la Patria 1846-1848 y Batallón de San Patricio” or “Defenders of the Fatherland 1846-1848 and the San Patricio Battalion” was inscribed in gold letters on the Wall of Honor in the Chambers of the Congress. Three hundred and ninety-four Mexican congressmen, along with Irish Ambassador to Mexico, Art Agnew, attended the ceremony recognizing the sacrifices made by the young Irish soldiers.

In 1959, a plaque was erected in Mexico City commemorating the Irish Heroes of Mexico. 53 The inscription of the plaque reads, “To the memory of Captain John Riley of the Clifden area, founder and leader of the Saint Patrick’s Battalion and those men under his command who gave their lives for Mexico during the U.S.-Mexican War of 1846-1848.” 54 Mexican sculptor, Lorenzo Rafael, designed the plaque that is located in San Jacinto Plaza, now known as Villa Obregón. Finally, in early September of 1997, Ireland and Mexico jointly released two postage stamps in commemoration of the 150th Anniversary of the San Patricio Battalion. John Riley’s lawsuit against the US

Author, Fairfax Downy, in his 1955 article in the American Heritage Magazine perpetuates the often repeated myth that Riley “dared bring suit against the United States in Cincinnati in 1849 to recompense him for damages received in his flogging and branding.” According to the research conducted by Wynn, for his dissertation, there is no record in Cincinnati of this lawsuit ever being filed. Wynn contacted the courts directly. would like to thank Martín for letting us reproduce his paper here.




    I am a mexican who lives in Frankfut am main Germany ,Thanks for write this article about John Reilly and the San Patricios for us Mexican they are our HEROES and we will never forget them they are part of our History VIVA MEXICO EIRE GO BRAGH

  2. I had a short visit to Clifton in 2016. It was thrilling to see the John Reilly memorial. I and some friends gathered one evening at the memorial and I led them in sing “The St. Patrick Battalion” by David Rovics. As a history teacher and singer-song writer and historian in the U.S., I have shared this history with my students, many of whom are Mexican and Mexican American. They were awestruck by what the St. Patrick Battalion did.

    I hope to be able to sing that song and songs from the Mexico and of Irish Americans at the 2018 St. Patrick Battalion commemoration . It would be an honor.

    Linda Boyle,

  3. Brave men. There is no logic in history. If the San Patricios were traitors to the USA and deserved death, then those (Bowie etc) at the Alamo (who had all signed a written oath of allegiance to Mexico) were traitors to Mexico and deserved death.

  4. Irish American, dad from Limerick living in California and very proud of Los San Patricio’s. Brave and honorable men who defended their follow Catholics against the Anglo protestant invasion of Mexico. We honor them annually at the San Francisco Irish-Mexican association.

  5. Catherine Eleanor Behan says:

    Gracias! A very interesting history.

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