The fighting Irish of Mexico.

• Author: Cramer, Marc
• Position: John Riley, US Army defector and Mexican hero

On the morning of September 10, 1847, Major John Riley was tied to a post in the plaza of San Angel on the outskirts of Mexico City. The shirt was ripped from his back as a muleteer stepped forward and laid on fifty lashes, reducing his flesh to pulp. Nearby, a branding iron bearing the letter "D" grew so hot it glowed. As Riley struggled to bite back the pain, the muleteer reached for the branding iron and burned a two-inch "D" into both sides of his face, scarring him for life. In the distance, fifty of Riley's soldiers, mostly Irishmen like himself, looked on with fear, one eye on Riley and the other on the gallows.

Branded, vilified, and eventually forgotten north of the Rio Grande, Riley and his companions are still venerated by Mexicans as heroes. A plaque erected in 1959 in the square of modern San Angel honors Riley and his followers. Commemorative coins and medals have been struck. Even a Mexican elementary school has been named in their honor. But what did this obscure Irishman and his followers do to inspire the polar extremes of hatred and adulation?

Shortly before the outbreak of the United States-Mexican War of 1846-48, Riley crossed the Rio Grande at Matamoros and defected, to form the most unusual fighting force in the history of America's foreign wars - the Saint Patrick's Battalion of the Mexican army.

When Mexico declared its independence from Spain and formed its own government in 1821, it soon became embroiled in a border dispute with its mighty neighbor to the north. After Mexico lost its territorial war with Texas in 1836, General Antonio Lopez de Santa Anna signed a peace treaty recognizing the land north of the Rio Grande as belonging to the newly declared Republic of Texas. For the next nine years, Texas was recognized as a sovereign nation by the United States, Great Britain, and France. But when Texas joined the Union, Mexicans were outraged and deemed the annexation an act of war.

Military forces soon began building up on either side of the border, the Mexican army of General Mariano Arista being the larger and more battle-hardened of the two. Across the Rio Grande at what was later to become Brownsville, Protestant officers dominated the Fifth Regiment of Infantry of General Zachary Taylor, who drew many of his enlisted men from the ranks of immigrants, often impoverished Irish Catholics who sought a better life in the "land of opportunity." Among them stood an obscure, uneducated private by the Gallic name of Sean O'Raghailligh, better known as John Riley.

When a U.S. scouting party was cut down by Mexican cavalry on April 25, 1846, Congress debated President James Polk's request for an immediate declaration of war. While many U.S. citizens supported the hostilities, others were outraged; their ranks included Henry David Thoreau, Daniel Webster, John Quincy Adams, and a freshman congressman from Illinois - Abraham Lincoln.

Ignoring the antiwar outcry and with the official declaration of war still pending, President Polk ordered his troops, including Riley's Company K of the Fifth Regiment...