The Mexican-American War (1846–48) has faded from many people’s minds, but this oft-forgotten conflict was actually the training ground for quite a few famous Civil War generals.
Robert E. Lee served in the Mexican-American War as an engineer. He had already been in the army for 17 years at that point but had never seen action. He initially served in Zachary Taylor’s portion of the army, building bridges and scouting. Then he moved to the Gulf Coast to serve with Winfield Scott, again as a scout. He saw action in multiple battles and proved essential in the Battle of Cerro Gordo when he found a route that would allow the US Army to attack the Mexicans’ flank.
Ulysses S. Grant initially served as a quartermaster in the war but was unhappy with the position, so he fought at the front instead, often on horseback. His most notable role was when, during the Battle of Chapultepec, he led the capture of a church then mounted a howitzer in the belfry to fire on the Mexicans below. Grant would later decry the war as “one of the most unjust ever waged by a stronger against a weaker nation.”
Stonewall Jackson also fought in the Battle of Chapultepec. During the battle, he disobeyed orders to withdraw because he felt pulling back would be more dangerous than continuing to fight against the better Mexican artillery; it turned out to be a good decision. Jackson received the most promotions during the war, attaining the ranks of second Lieutenant of artillery (brevet), second lieutenant (permanent), first lieutenant (permanent), captain (brevet), and major (brevet).
Future generals James Longstreet and George Pickett were friends in the 8th Infantry during the Mexican-American War. Both received brevet promotions for their actions in battle. During the Battle of Chapultepec, Longstreet, who was carrying the colors, was wounded in the leg. He passed them on to Pickett, and Pickett fought his way to the top of the fort to mount the colors and signal the fortress’s surrender.
Other future famous Civil War generals who served in the Mexican-American War included George McClellan, Ambrose Burnside, George Meade, Winfield Scott Hancock, P.G.T. Beauregard, Albert Johnston, Joseph Johnston, George Thomas, Edmund Smith, Braxton Bragg, and Joseph Hooker.
Read more about how the Mexican-American war shaped Civil War generals on the PBS website. Or find original documents pertaining to the service of Civil War generals during the Mexican-American War in Fold3′s Letters Received by the Adjutant General, 1822-1860.