This Day in American Military History

13 September 1847: The United States prevailed in the Battle of Chapultepec, at Chapultepec Castle, Mexico City, the last major battle of the Mexican-American War. The next day, General Winfield Scott marched U.S. troops into the city and raised the American flag over the Mexican National Palace—the “Halls of Montezuma” later celebrated in the famous Marine Corps Hymn. A mass execution of 30 San Patricios took place as the American flag was raised over Chapultepec, ordered by Winfield Scott. The San Patricios, members of the Saint Patrick’s Battalion, were predominately Catholic Irish U.S. Army deserters who joined the Mexican side. With 20 San Patricio executions earlier in the week, it comprised the U.S.’s largest mass execution.

American officers at the battle included Robert E. Lee, P. G. T. Beauregard, Joseph E. Johnston, Ulysses S. Grant, Stonewall Jackson, and many other now-famous men.

Brandus, Paul. This Day in U.S. Military History (pp. 223-224). Bernan Press. Kindle Edition.