‘In Memory of the Irish Soldiers of the Heroic San Patricio Battalion, Martyrs who gave their Lives for the cause of Mexico during the Unjust American Invasion of 1847.’
- Inscription from a stone plaque erected at Villa Obregón, a suburb of Mexico City.
The San Patricios: the Irish who fought for Mexico
- Overview of chapter two of Courage and Conflict

Today, in Mexico City, there stands a monument to a group comprised mostly of Irish and German soldiers who fought and died in the Mexican-American war of 1846-1848. These soldiers, known as the San Patricios, and their Galway born commanding officer, John Riley, have passed into legend but the details of their story are often misunderstood or misrepresented. As the above quotation makes clear, the soldiers of the San Patricios are still viewed as heroes in Mexico. To the Mexicans of the 1840s the San Patricios were men of character and honour who fought and died to protect their country from foreign aggression. To the Americans, the San Patricios were a gang of traitorous mercenaries who joined forces with the enemy. Of course, the epic tale of the San Patricios is much more complex than a straight conflict between good and bad. It is a story of ordinary men who were caught up in great events and it was the choices made by these men, almost all of them emigrants, which would see the San Patricios at the centre of a vicious war, a war that would ultimately decide who would control the vastness of the North American continent.
In 1845, John Riley, a former soldier in the British army left Ireland for the United States. Within months, like thousands of other immigrants to America, he had joined a US army which was frantically recruiting soldiers for the coming war with Mexico. Unfortunately for these emigrants, nativist prejudice was nearing its zenith. Driven by intense anti-immigrant and anti-Catholic sentiments, nativists were common throughout US society and the US army was not free of this blight. Many of the higher ranks openly proclaimed nativist ideals and these officers had few qualms about putting their prejudice into practice. The Irish and Germans were routinely singled out for beatings, torture, and a variety of other bizarre punishments. Consequently, the army was plagued by desertions. John Riley was one of these and in April 1846 he escaped to Mexican territory. The Galway-man was experienced with artillery weapons and he impressed the Mexican generals, who awarded him an officer’s commission. From that time onwards Riley gathered together other foreigners who had deserted the US army and from these efforts the Battalion of St. Patrick, the San Patricios, was born.
Courage and Conflict tells the story of the San Patricios by explaining who they were and why they fought for the Mexicans. It follows their careers in the Mexican army, describes their battles and tells how they became a vital part of the Mexican war effort. Yet for all their successes they would ultimately be on the losing side as the US army won a series of major victories over its Mexican opponents. Many of the San Patricios would be captured and publicly executed in mass executions. Other San Patricios were publicly tortured amid scenes that shocked popular opinion across Mexico and the US. Courage and Conflict also delves into the aftermath of the war and attempts to answer the conundrum of why the San Patricios were forgotten, not least by Irish-Americans, in the decades after. It is a story almost as dramatic as that of the San Patricios and casts a light on how history can be manipulated, twisted and forgotten to suit the needs of those who come after.
In 1845, John Riley, a former soldier in the British army left Ireland for the United States. Within months, like thousands of other immigrants to America, he had joined a US army which was frantically recruiting soldiers for the coming war with Mexico. Unfortunately for these emigrants, nativist prejudice was nearing its zenith. Driven by intense anti-immigrant and anti-Catholic sentiments, nativists were common throughout US society and the US army was not free of this blight. Many of the higher ranks openly proclaimed nativist ideals and these officers had few qualms about putting their prejudice into practice. The Irish and Germans were routinely singled out for beatings, torture, and a variety of other bizarre punishments. Consequently, the army was plagued by desertions. John Riley was one of these and in April 1846 he escaped to Mexican territory. The Galway-man was experienced with artillery weapons and he impressed the Mexican generals, who awarded him an officer’s commission. From that time onwards Riley gathered together other foreigners who had deserted the US army and from these efforts the Battalion of St. Patrick, the San Patricios, was born.
Courage and Conflict tells the story of the San Patricios by explaining who they were and why they fought for the Mexicans. It follows their careers in the Mexican army, describes their battles and tells how they became a vital part of the Mexican war effort. Yet for all their successes they would ultimately be on the losing side as the US army won a series of major victories over its Mexican opponents. Many of the San Patricios would be captured and publicly executed in mass executions. Other San Patricios were publicly tortured amid scenes that shocked popular opinion across Mexico and the US. Courage and Conflict also delves into the aftermath of the war and attempts to answer the conundrum of why the San Patricios were forgotten, not least by Irish-Americans, in the decades after. It is a story almost as dramatic as that of the San Patricios and casts a light on how history can be manipulated, twisted and forgotten to suit the needs of those who come after.
Return to Courage and Conflict
Copyright, Ian Kenneally - See also johnboyleoreilly.com and revolutionpapers.com