Battle of Churubusco
Thirty men from the Saint Patrick's Battalion, a group of former United States Army soldiers who joined the Mexican side, were executed "en masse" during the battle. They had been previously captured at the Battle of Churubusco. Colonel William S. Harney specified that they were to be hanged with Chapultepec in view and that the precise moment of their death was to occur when the U.S. flag replaced the Mexican tricolor atop the citadel.