The San Patricios

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The court-martial of Capt. John O’Reilly was one of twenty-nine convened by the United States Army at the San Angel prison camp in Mexico on August 28, 1847: thirty-six other men of O’Reilly’s San Patricio Battalion faced courts-martial on that same day at nearby Tacubaya.

The trials were swift. The prosecution established that each of the accused men had deserted from U.S. forces and then had fought against them in the captain’s Mexican outfit. Almost every man tried at San Angel and Tacubaya was convicted and sentenced to be hanged.

“These sentences, which would have been appropriate at any time, were particularly so now,” wrote Raphael Semmes, a Navy lieutenant who had served as a volunteer with the U.S. Marines in Mexico. “There were many foreigners in our ranks … and the enemy was making every effort still to entice them away. The salvation of the army might depend upon an example being made of these dishonored and dishonorable men.”

Semmes was a devout Roman Catholic, and like others of his faith serving in the U.S. forces, he believed that the men of the San Patricio Battalion had done a great disservice to American Catholics. Semmes recalled that “the brave Irish, who remained faithful to us … were more rejoiced at the event [of the convictions] than the native-born Americans even, as they felt keenly the stigma which this conduct of their countrymen had cast upon them.”

The U.S. soldiers reserved much of their anger for the mysterious John O’Reilly, whom they regarded as the archtraitor. He was the man who had led the others astray and had been seen in the middle of the fiercest fighting from Monterrey to Churubusco. It had been proved at his court-martial that he was formerly Pvt. John Reilly of K Company, 5th U.S. Infantry, and that he had deserted from General Taylor’s army when it reached the Rio Grande in April 1846. O’Reilly offered little in the way of a defense, but that little was artful: He considered himself a Mexican national, but he had been born in Ireland. “He expects to be hung,” wrote the U.S. medical officer at San Angel, “but denies the justice of it, as he calls himself a British subject.’

If the incident at Santa Isabel could outrage the young Lincoln, perhaps it convinced John O’Reilly that he was on the wrong side of a war.

O’Reilly’s Mexican nationality was endorsed by no less a sponsor than Santa Anna, who was then negotiating with President Folk’s envoy to end the war. He wanted the survivors of the San Patricio Battalion to be guaranteed prisoner-of-war status. The prisoner’s emphasis on his Irish birth had an effect as well. The British position on nationality in 1847 was “Once a Briton, always a Briton,” and there was no such thing as naturalization. Charles Bankhead, Britain’s minister to Mexico, visited the headquarters of Gen. Winfield Scott and volunteered to serve as an intermediary in a prisoner exchange. Bankhead was followed to Scott’s headquarters by the archbishop of Mexico City. Everyone was seeking the exchange, outright release, or ransom of the captain.

Scott was polite and gentlemanly to all his distinguished visitors, but he made his position clear. It was his duty to review the courts-martial and either approve or disapprove the sen- tences, and he assured the dignitaries that he would assess the captain’s case with the same attention to evidence as the others.

These visits were nevertheless an extraordinary intervention on behalf of a convicted Army deserter, but then “Brave Reilli” was a great war hero south of the border. A Mexican historian described him as “ un soldado de fortuna, aventurera de las armas, hombre gentil y apuesto, de gran simpática y fácil palabra, inquieta y temerario .” (He was “a soldier of fortune, a master of arms, a gentle, well-groomed, wellspoken, restless man of action who had great sympathy for Mexico.”)

Little is known about O’Reilly’s past (even the spelling of his name varies from Riley to Reilly to O’Rily ) beyond the fact that he was born in County Galway and was generally reported to have been a British army sergeant who deserted shortly after his regiment arrived in Canada in 1843. At the time of the trial he became the object of increasingly fabulous speculation—he had been a brilliant instructor of cadets at West Point, he was deeply involved with a propertied Mexican lady—but all the stories were promulgated to explain the inexplicable. John O’Reilly had to be more than a mere renegade private because he had confounded the U.S. Army for eighteen months.

The United States annexed Texas in December of 1845, and Gen. Zachary Taylor’s armv moved into the new state from Louisiana. When Taylor’s forces were ordered south of the Rio Nueces, every soldier knew what it meant. “We were sent here to provoke a fight,” wrote one officer. As Taylor advanced on the Rio Grande, the Mexican general Mariano Arista, hoping to avoid a clash with the U.S. troops before he could ascertain his orders, drew his patrols back to Matamoros. By moving south of the Rio Grande, he left the settlement of Santa Isabel to the Yankees.