5 Things You Didn’t Know About The Mexican-American War

On May 13, 1846, President Polk declared war on Mexico following a border dispute over Texas.  Some viewed the war as a blatant land grab by the Americans and President Polk's reputation suffered as a result. Here are five things you probably didn’t know about the Mexican-American War...


Polk Wanted to Buy the Land, But Mexico Refused Diplomat John Slidell was sent to Mexico in 1845 by President James Polk to settle a border dispute with Mexico or buy their territories in California and New Mexico for up to $25 million. The Mexicans refused to sell, so Polk sent Zachary Taylor, along with 4,000 troops to occupy land between the Rio Grande and Nueces River, which Mexico claimed as theirs. Mexico responded by sending their own troops, which attacked an American patrol. On May 13, 1846, Congress voted to declare war on Mexico by an overwhelming margin.

The Conflict Was Nicknamed “Mr. Polk’s War” An anti-war movement arose as a result of the Mexican-American War as some viewed it as a land grab and referred to it as “Mr. Polk’s War,” and others saw it as a way to add additional slave states. Abraham Lincoln was a freshman in congress at the time and said the original skirmish was provoked because it occurred on land belonging to Mexico. His resolutions against the Mexican-American War brought him to the public’s attention but harmed his reputation with those who were pro-war.


The War Marked The Debut of Several Future Civil War Generals Along with future presidents Zachary Taylor and Franklin Pierce, the U.S. force in Mexico included many officers who later made their name on the battlefields of the Civil War. Union Generals Ulysses S. Grant, George Meade and George McClellan all served, as did many of their Confederate adversaries such as Robert E. Lee, Stonewall Jackson and George Pickett. Lee, then a captain in the Army Corps of Engineers, emerged from the war a hero at the Battles of Cerro Gordo and Contreras.

The Casualty Rate Was Enormous The U.S. never a lost a major battle during the Mexican-American War, but the victory still proved costly. Of the 79,000 American troops who took part, 13,200 died. The vast majority were victims of diseases such as dysentery, yellow fever, malaria and smallpox. According to scholar V.J. Cirillo, a higher percentage of U.S. troops died from sickness during the Mexican invasion than any war in American history. Mexican casualties were also high, with most historians estimating as many as 25,000 dead troops and civilians.

The War Reduced The Size of Mexico by More Than Half Mexico relinquished its claim to Texas under the Treaty of Guadalupe Hidalgo and was forced to accept $15 million for an enormous part of their territory. The lands that Mexico ceded all became future states. They included the areas that encompass California, Nevada, New Mexico, Arizona, Utah, Wyoming, Colorado, Kansas, and Oklahoma.