St. Patrick’s Battalion, a unit of the Mexican Army, was composed mainly of Irish Catholic immigrants who deserted the U.S. Army and fled to Mexico during the war, which lasted from 1846-48.

St. Patrick’s Battalion. The proud and patriotic service of Irish Americans—whether first-generation naturalized immigrants or stateside-born, and whether Catholic or Protestant—in wartime ...

On St. Patrick’s Day, Mexicans celebrate in honor of the Irish battalion that defended their country against the invading United States Army in the 1840s.

The first St. Patrick's Day parade currently on record was held in St. Augustine, Florida, in 1601, historians say. Not, as some might assume, on the Emerald Isle.