Watson held the rank of brevet lieutenant colonel in the Marines during the Mexican War. He commanded a Marine battalion that reinforced the army of Winfield Scott shortly before the Battle for Mexico City. (Watson had served under Winfield Scott in 1813 and was a veteran Marine.)
During the Mexican War, Watson held the rank of brevet lieutenant colonel in the Marines. He led a Marine battalion that supported Winfield Scott's army just prior to the Battle of Mexico City.  (Watson had previously served under Winfield Scott in 1813 and was an experienced Marine.)