Meet the Irish American battalion that en masse defected to Mexico

A bit of far off Irish-American-Mexican history brings to light a lesser-known chapter of Irish military service – the time that 265 Irish service members defected.

Some called them heroes; others called them traitors. The Irish immigrants who joined the Army in the 1840s decided when the war broke out between the US and Mexico that they wanted none of it.

Right after the US annexed Texas in 1845, both Mexico and America sent military members to the newly created and shared border.

1845 America was a tumultuous place – Florida was admitted as a state, the Great Fire of Pittsburg destroyed much of the city, and Frederick Douglass's Narrative of the Life of Frederick Douglass, an American Slave, was published.

Thoreau embarked on his two-year experiment to live in the woods at Walden Pond, a huge fire destroyed lots of New York, and the US Naval Academy officially opened its doors. Johnny Appleseed died in 1845, and Edmonia Lewis died.

A lot was going on, no more so evident than within the US Army. In 1845, the Army was a hodgepodge of service personnel, with diverse backgrounds, much like it is today. Service members were from all over the world, especially from western European countries, all of which had distinct and robust Catholic population groups. Many immigrant service members were blatantly disrespected and discriminated against by "native-born Americans," which led to widespread unrest and low morale. Adding to that was most of the immigrant soldiers were Catholic, outliers in the very protestant America of the time.

So back to the Irish battalion. No one is quite sure exactly how it happened. Still, most historians agree that the widespread abuse of immigrant personnel coupled with the very low troop commitment levels led to a huge percentage of the Army feeling invisible, disenfranchised, and without appropriate ways to voice their frustrations.

Much of the American public felt that the annexation of Texas was useless – an expansionist war was nothing the young country needed. One of the most vocal about the uselessness of the expansion was Abraham Lincoln, who was quoted as not surprised that the Army saw so many deserters during this time.

While the Army was struggling to hold rank, the Mexican military saw an opportunity to infiltrate and spread propaganda, which is exactly what they did.

Several Mexican Army generals sent messages targeted toward immigrant personnel stationed at the Texas border. These messages crossed the Rio Grande River. All held one core focus – that immigrant service members should abandon their American Army posts and join their Catholic brothers in arms in the Mexican military. The messages offered Mexican citizenship and huge land grants – as much as 320 acres for privates.

More than 5,000 US soldiers would desert their posts throughout the war, and more than 40,000 simply disappeared in Mexico.

The Irish defectors were known as the St. Patrick's Battalion, and their Mexican brothers-in-arms called them "The Red Company" because so many of them had red hair and ruddy complexions.

The battalion's flag showed a winged harp, three-leaf clovers, and the motto, "Irish till the end of time," written in Gaelic. The battalion fought alongside the Mexican Army as part of a rolling rearguard that worked to defend against as the US military advanced further into Mexico.

In the final days of the final battle, over 60 deserters were captured, and fifty of them were executed. The Mexican Army pleaded for mercy and leniency, but only a handful of the Irish deserters were actually pardoned.

But, of those who were pardoned, it wasn't as easy as just walking away. The men had to receive 50 lashes on their backs while being tied to trees in the plaza at Churubusco, and their faces were branded with "D" for deserter. To this day, the Irish battalion is honored every year in festivals throughout Mexico and Ireland.