Saint Patrick's Battalion Flag / Erin Go Bragh Tasse

The Saint Patrick's Battalion (Spanish: Batallón de San Patricio, later reorganized as the Foreign Legion of Patricios), formed and led by John Riley, was a unit of 175 to several hundred (accounts vary) immigrants and expatriates of European descent who fought as part of the Mexican Army against the United States in the Mexican–American War of 1846–48. Most of the battalion's members had deserted or defected from the United States Army.