Captain Myers was stationed at Fort Moultrie from 1842–1845. During the Mexican–American War, Myers served under Zachary Taylor at the Battle of Palo Alto and the Battle of Resaca de la Palma; his "gallant and meritorious conduct" thereat earned him a promotion to brevetted major. After his transfer to Winfield Scott's command, Myers fought at the Battle of Churubusco (receiving a brevetted promotion to colonel or lieutenant colonel for "gallant conduct"), and was the Army of Mexico's chief quartermaster from April–June 1848.