August 20 - Anniversary of the Battle of Churubusco
The Battle of Churubusco took place on August 20, 1847, while Santa Anna's army was in retreat from the Battle of Contreras (Padierna), Mexican–American War. After defeating the Mexican army at Churubusco, the U.S. Army was only 5 miles (8 km) away from Mexico City.
The Saint Patrick's Battalion (Spanish: Batallón de San Patricio), formed and led by John Riley, was a unit of 175 to several hundred immigrants (accounts vary) and expatriates of European descent who fought as part of the Mexican Army against the United States in the Mexican–American War of 1846–8. Most of the battalion's members had deserted or defected from the United States Army. The Battalion served as an artillery unit for much of the war. Despite later being formally designated as two infantry companies, it still retained artillery pieces throughout the conflict. In many ways, the battalion acted as the sole Mexican counterbalance to the recent U.S. innovation of horse artillery. The "San Patricios" were responsible for the toughest battles encountered by the United States in its invasion of Mexico, with Ulysses S. Grant remarking that "Churubusco proved to be about the severest battle fought in the valley of Mexico"
https://en.wikipedia.org/wiki/Saint_Patrick%27s_Battalion
The San Patricios used this battle as a chance to settle old scores with U.S. troops. "The large number of officers killed in the affair was ... ascribed to them, as for the gratification of their revenge they aimed at no other objects during the engagement". At some point during the fighting for the convent, two American officers led fifteen men against a point in the Mexican defences, and mistook San Patricio members for friendly U.S. army troops; the San Patricios opened fire on them, killing and wounding all but one of the group. Though hopelessly outnumbered and under-equipped, the defenders repelled the attacking U.S. forces with heavy losses until their ammunition ran out and a Mexican officer raised the white flag of surrender. Officer Patrick Dalton of the San Patricios tore the white flag down, prompting Gen. Pedro Anaya to order his men to fight on, with their bare hands if necessary. American Private Ballentine reported that when the Mexicans attempted to raise the white flag two more times, members of the San Patricios shot and killed them. After brutal close-quarters fighting with bayonets and sabers through the halls and rooms inside the convent, U.S. Army Captain James M. Smith suggested a surrender after raising his white handkerchief. Following the U.S. victory, the Americans "ventilated their vocabulary of Saxon expletives, not very "courteously," on Riley and his beautiful disciples of St. Patrick."