The war between Mexico and the United States
The United States invades Mexico, occupies its capital and takes about half its territory, from Texas to California, in the Treaty of Guadalupe Hidalgo.
- A Wicked War: Polk, Clay, Lincoln, and the 1846 U.S. Invasion of Mexico — Amy S. Greenberg, Alfred A. Knopf (2012)
- México frente a Estados Unidos: un ensayo histórico, 1776–2000 — Josefina Zoraida Vázquez and Lorenzo Meyer, Fondo de Cultura Económica (2001)
- War of a Thousand Deserts: Indian Raids and the U.S.-Mexican War — Brian DeLay, Yale University Press (2008)
- The Course of Mexican History — Michael C. Meyer, William L. Sherman and Susan M. Deeds, Oxford University Press (2014)
- Personal Memoirs of U. S. Grant — Ulysses S. Grant, Charles L. Webster & Company (1885)
Before the war
When Mexico won independence in 1821 its northern frontier, from Texas to California, was vast and thinly settled. To fill Texas, Mexico invited American colonists, who soon outnumbered Mexican tejanos, brought enslaved people despite Mexico’s abolition of slavery in 1829, and resisted central control. In 1836 they rebelled and won independence after the battles of the Alamo and San Jacinto; Mexico never recognised it.
- The Course of Mexican History — Michael C. Meyer, William L. Sherman and Susan M. Deeds, Oxford University Press (2014)
- México frente a Estados Unidos: un ensayo histórico, 1776–2000 — Josefina Zoraida Vázquez and Lorenzo Meyer, Fondo de Cultura Económica (2001)
Meanwhile Comanche and Apache raids devastated northern Mexico in the 1830s and 1840s, killing thousands and leaving the region poor and divided, which historian Brian DeLay argues made it far easier for the United States to conquer.
- War of a Thousand Deserts: Indian Raids and the U.S.-Mexican War — Brian DeLay, Yale University Press (2008)
The war
The United States annexed Texas in 1845. President James K. Polk, who wanted California above all, sent troops under Zachary Taylor into the land between the Nueces River and the Rio Grande, which both countries claimed. After a skirmish there in April 1846, Polk told Congress Mexico had “shed American blood upon the American soil”, and Congress declared war in May.
- A Wicked War: Polk, Clay, Lincoln, and the 1846 U.S. Invasion of Mexico — Amy S. Greenberg, Alfred A. Knopf (2012)
US forces took New Mexico and California, beat Mexican armies in the north, and in 1847 Winfield Scott landed at Veracruz and fought his way to Mexico City. On 13 September 1847 US troops stormed Chapultepec Castle, then the military academy. According to Mexican tradition six young cadets, the Niños Héroes, died defending it, one of them wrapping himself in the flag and leaping from the walls; historians treat the leap as legend, but the cadets’ deaths are real. Mexico City fell the next day.
- The Course of Mexican History — Michael C. Meyer, William L. Sherman and Susan M. Deeds, Oxford University Press (2014)
- México frente a Estados Unidos: un ensayo histórico, 1776–2000 — Josefina Zoraida Vázquez and Lorenzo Meyer, Fondo de Cultura Económica (2001)
Mexico was politically fractured, with presidents changing repeatedly and General Antonio López de Santa Anna returning to power yet again. Irish Catholic deserters from the US army, the San Patricios, fought for Mexico, and many were hanged after their capture; Mexico still honours them.
- A Wicked War: Polk, Clay, Lincoln, and the 1846 U.S. Invasion of Mexico — Amy S. Greenberg, Alfred A. Knopf (2012)
- The Course of Mexican History — Michael C. Meyer, William L. Sherman and Susan M. Deeds, Oxford University Press (2014)
- A Wicked War: Polk, Clay, Lincoln, and the 1846 U.S. Invasion of Mexico — Amy S. Greenberg, Alfred A. Knopf (2012)
The treaty
The Treaty of Guadalupe Hidalgo, signed on 2 February 1848, set the border at the Rio Grande and ceded what became California, Nevada, Utah and most of Arizona and New Mexico, plus parts of Colorado and Wyoming. Counting Texas, Mexico lost about half its territory; the United States paid $15 million. The Gadsden Purchase of 1853 added a further strip of southern Arizona and New Mexico.
- The Course of Mexican History — Michael C. Meyer, William L. Sherman and Susan M. Deeds, Oxford University Press (2014)
- A Wicked War: Polk, Clay, Lincoln, and the 1846 U.S. Invasion of Mexico — Amy S. Greenberg, Alfred A. Knopf (2012)
Some 80,000 to 100,000 Mexicans lived in the ceded lands. The treaty promised them citizenship and protection of their property, but in practice many lost their land through courts, fraud and violence over the following decades.
- Line in the Sand: A History of the Western U.S.-Mexico Border — Rachel St. John, Princeton University Press (2011)
- The Course of Mexican History — Michael C. Meyer, William L. Sherman and Susan M. Deeds, Oxford University Press (2014)
Legacy
For the United States, the conquest set off the crisis over slavery in the new territories that led to the Civil War. For Mexico, the defeat was a trauma that helped push the liberals of the Reforma to rebuild the state. Mexican schools teach it as the “intervención estadounidense”, and the monument to the Niños Héroes at Chapultepec is a national shrine; when US President Harry Truman laid a wreath there in 1947, it made headlines in Mexico.
- México frente a Estados Unidos: un ensayo histórico, 1776–2000 — Josefina Zoraida Vázquez and Lorenzo Meyer, Fondo de Cultura Económica (2001)
- Mexico: Biography of Power. A History of Modern Mexico, 1810–1996 — Enrique Krauze, HarperCollins (1997)
An unjust war of conquest by an expansionist neighbour that provoked a fight in disputed territory to seize land it had already tried to buy. Mexico's divided, bankrupt governments and rival generals share some blame for the defeat, but the war is remembered as a theft of half the nation.
- México frente a Estados Unidos: un ensayo histórico, 1776–2000 — Josefina Zoraida Vázquez and Lorenzo Meyer, Fondo de Cultura Económica (2001)
- Mexico: Biography of Power. A History of Modern Mexico, 1810–1996 — Enrique Krauze, HarperCollins (1997)
President James K. Polk claimed Mexico had "shed American blood upon the American soil" in the disputed zone north of the Rio Grande, and many Americans saw expansion to the Pacific as Manifest Destiny.
- A Wicked War: Polk, Clay, Lincoln, and the 1846 U.S. Invasion of Mexico — Amy S. Greenberg, Alfred A. Knopf (2012)
Many Americans opposed the war at the time, including the young congressman Abraham Lincoln, who challenged Polk to identify the "spot" where blood had been shed. Ulysses S. Grant, who fought in it, later called it "one of the most unjust ever waged by a stronger against a weaker nation". Most US historians today see it as a war of conquest.
- A Wicked War: Polk, Clay, Lincoln, and the 1846 U.S. Invasion of Mexico — Amy S. Greenberg, Alfred A. Knopf (2012)
- Personal Memoirs of U. S. Grant — Ulysses S. Grant, Charles L. Webster & Company (1885)
Why it matters today
In Mexico this is "la Intervención estadounidense", a national humiliation taught in every school, remembered through the Niños Héroes of Chapultepec, and the root of a lasting wariness of the powerful neighbour. When Mexicans joke that "we didn't cross the border, the border crossed us", this is what they mean.
Most Americans know little about this war, though it gave the country California, Texas and the Southwest. Its conquests reopened the fight over whether slavery could spread west, helping cause the Civil War, and they made the Mexican American story part of the American story from the start.