According to the official website of the U.S. Marines, "the Halls of Montezuma" is part of the first line of that military organization's official "Marine's Hymn." On occasion, the phrase is used as an alternate title for the song.
"The Halls of Montezuma" also refers the Battle of Chapultepec that marines fought during the Mexican-American War. History.com indicates that this clash essentially ended the hostilities. Although the Mexican army was larger, the American forces had superior leadership, training and supplies. General Winfield Scott led his forces from Vera Cruz to Mexico City, stopping at Chapultepec to capture the fortress. Following this success, the Americans entered Mexico's capital city and flew the stars and stripes over the Mexican National Palace or "The Halls of Montezuma."