What is the connection between Mexico and Ireland?
In 1846, thousands of immigrants, mostly Irish, joined the US army and were sent with Gen. Zachary Taylor's army to invade Mexico in what some historians have called a war of Manifest Destiny.
Dubious about why they were fighting a Catholic country, and fed up with mistreatment from their Anglo-Protestant officers, hundreds of Irish and other immigrants deserted Taylor's army and joined forces with Mexico. Led by Captain John Riley of County Galway, they called themselves the St. Patrick's Battalion---in Spanish, the San Patricios.
They fought bravely in most of the campaigns of the two-year conflict, but their efforts failed to stem the Yankee onslaught. Soon the US Army occupied the halls of Montezuma, and Mexico eventually surrendered, ceding nearly half its territory to the United States.
Toward the end of the conflict, at the Battle of Churubsco, 83 San Patricios were captured, and 72 were court-martialed. Of this number, 50 were sentenced to be hanged and 16 were flogged and branded on their cheeks with the letter "D" for deserter.
Mexicans see them as heroes, honoring them every Sept. 12 with a special commemoration. In 1993, the Irish began their own ceremony to honor them in Clifden, Galway, Riley's hometown.
From The San Patricios: Mexico's Fighting Irish by Mark R. Day