The impact of the Mexican War
The Mexican War enhanced the prestige of the United States Military Academy at West Point, and many of its graduates became household names. The Army Corps of Engineers and its officers, in particular Robert E. Lee, were esteemed for their professionalism under fire. Several political careers were launched by veterans, including by Franklin Pierce, who defeated his fellow veteran Winfield Scott for the presidency in 1852. Zachary Taylor was elected president in 1848, as Polk had feared when the general developed his reputation early in the war, but Polk did not run for re-election against him, having previously pledged to serve only one term.
The Mexican War was the first experience of combat for many of the officers who later served in the American Civil War, on both sides of the conflict. The leadership of the young junior officers and their observations of how their men behaved under fire, and among the civilian population of occupied territories, did much to inform their treatment of their men in the later conflict. They also established the tactics which would later be used in the Civil War, many of which by then had become outdated by the improvements in weapons. The coordinated operations between the army and navy were repeated in the Civil War along the rivers and inlets of the American coast.
The Mexican War led to regional debates in Congress, over slavery in the new states and territories from the lands acquired, for which Mexico was compensated in the Treaty of Guadalupe Hidalgo. Mexico was given $15 million in compensation for the loss of land and the United States assumed responsibility for debts of the Mexican government to settlers in the new American territories of $3.25 million dollars. The vast land acquisition became known as the Mexican Cession as a result of the compensation, rather than the conquest which it was. The amount paid was less than half of what Polk had been willing to pay for the land before the war.
Within one year of the end of the war, gold was discovered in California, followed by the silver strikes in Nevada. Within a decade the Pony Express was connecting California with the east, and plans were underway for a transcontinental railroad, which were disrupted by the Civil War. In 1848 the town of San Francisco had about 1,000 inhabitants. At the end of the following year it held more than 25,000. Other areas within the land of the Mexican Cession grew far more slowly, occupied by the Native American tribes hostile to American settlement.
As America became more divided over the issue of slavery many pointed to the Mexican War as the point of no return. When former president Grant wrote his memoirs, which included his service in the Mexican War, he wrote, “The Southern rebellion was largely the outgrowth of the Mexican war.” Unlike Robert E. Lee, Grant left the army for a time, returning as a volunteer when the Civil War broke out. So did several other officers, as competition for posts became stiffer in the peacetime army. What posts existed were largely isolated outposts among the Indians, and military careers featured slow advancement. Even Robert E. Lee was still a Colonel when the Civil War erupted, more than a decade following the Mexican War.
Where do we find this stuff? Here are our sources:
“Personal Memoirs of U.S. Grant”, by Ulysses S. Grant, 1885
“Lessons of the Mexican War”, by Norman A. Graebner, Pacific Historical Review, 1978, online
“Fremont Steals California”, by Sally Denton, American Heritage Magazine, Winter, 2011
“The US and Mexico at War”, by Donald S. Frazier, 1998
“So Far From God: The U. S. War with Mexico, by John Eisenhower, 1989
“Santa Anna of Mexico”, by Will Fowler, 2007
“The San Patricios”, by James Callaghan, American Heritage Magazine, November 1995
“A Nice Piece of Real Estate”, by Richard Reinhardt, American Heritage Magazine, December 1971