Mexican American_War

Photo from the movie Cinco de Mayo: Batalla.


Monday, May 5 is Cinco de Mayo, whose historic value is overshadowed by drunken celebration.

The day honors the 1862 Mexican victory over French forces in the battle of Puebla. 

Even more overlooked by Americans is their war with Mexico from 1846-48, which expanded the United States to the Pacific and is seen by many as a precursor to the Civil War.  Some criticize the American role as the aggressor in the war, and the conflict remains an integral part of Mexican national identity. 

“Mexicans still remember losing their entire northern territory,” said Dr. Gary Long, who teaches world history at Blackburn College. “The war remains a key aspect of Mexico’s national memory, much more than in the U.S.”

Tensions had simmered over the Republic of Texas for the previous decade, and many Americans remained bitter over the Mexican capture of the Alamo in 1836. Mexico never recognized Texan independence and ceased diplomatic relations after the U.S. annexation of Texas in 1845. 

The United States also cast an eye on the sparsely populated northern Mexican territories of California and New Mexico.  President James Polk was rebuffed in efforts to purchase the territories, offering to forgive Mexican debt in the deal. Still, the U.S. desired expansion, reflected in an 1845 editorial that coined the term “manifest destiny.”

Among the issues was the Texas border dispute, as the U.S. claimed their territory stretched to the Rio Grande, while Mexico argued for the Nueces River, to the north. Efforts to negotiate the border were rejected in Mexico City, as were attempts to buy the northern lands. Strengthening the American position was a sizable military force under Zachary Taylor that Polk ordered into Texas.  But Mexico refused, and Polk directed Taylor to march to the Rio Grande.

Engagements near the river ensued in April 1846, and Congress overwhelmingly declared war on May 13. The war proved equally popular with the public, although Whigs frequently criticized the war. Among them was Abraham Lincoln, a U.S. House freshman who drew widespread rebuke for his 1847 “Spot Resolutions,” demanding that Polk “establish…the particular spot” where the first blood had been shed. 

“Lincoln wanted to know why, where, and when the war started,” said Dr. James Cornelius of the Abraham Lincoln Presidential Library and Museum in Springfield. “He questioned Polk’s assertion of an attack on American citizens on American soil, because there was no international agreement on the border.” 

Taylor’s campaign spread into northern Mexico, where his success made him a national hero and lifted him into the Presidency in 1848. Meanwhile, small American forces secured the New Mexico and California territories with grueling marches over desolate lands.

To the south, Winfield Scott led a campaign against Mexico City, beginning with a landing at Veracruz in March 1847, the first joint amphibious offensive in American military history. The capital fell on September 13.

Hostilities formally ended with the Treaty of Guadalupe Hidalgo on Feb. 2, 1848. As part of the agreement, the U.S. paid $15 million for the northern territories, land now comprising much of the American central west and southwest.

Some 6,500 Illinoisans served in the war. Although usually outnumbered, the Americans held distinct advantages in weaponry and generalship. U.S casualties numbered over 17,400, while Mexico lost an estimated 25,000.

As elsewhere, Illinois is dotted with names of Mexican landmarks, including the town of Cerro Gordo in Piatt County and Camargo Township in Douglas County. At the battle of Cerro Gordo on April 18, 1847, members of the Fourth Illinois captured the artificial leg of Mexican commander Antonio Lopez de Santa Anna. The leg remains on display at the Illinois State Military Museum in Springfield.

Numerous Civil War leaders fought in the war, including Ulysses S. Grant and Robert E. Lee. Many have called the war a “dress rehearsal” for the Civil War. The territories that the U.S. won exacerbated the slavery question, as disputes quickly arose on spreading slavery westward. As a result, many believe that the Mexican-American War contributed to the American Civil War.

Historians in both nations frequently charge that the U.S. provoked a war against a weaker opponent. Grant wrote that the war was “one of the most unjust ever waged by a stronger against a weaker nation.”

However, Mexico contributed to its own weakness. The nation endured thirty-six changes in presidency between 1833 and 1855 and was threatened with revolt even during its war with America.   Santa Anna himself ruled Mexico eleven times before his death in 1876. A heavy debtor nation for decades, Mexican internal strife induced France to declare war in 1861.

Today, the war is relegated to a few paragraphs in American history textbooks and a handful of battlefield memorials in the Southwest. By comparison, Mexicans even today retain a level of bitterness and humiliation for the defeat and loss of their territory. 


Tom Emery is a freelance writer and researcher from Carlinville, Ill. He may be reached at 217-710-8392 or