The Mexican American War has its antecedents in the expansionist policies of the United States, which had been observed since 1809: the purchase of Louisiana in 1803, the signing of the Adams-Onis Treaty of 1819, with which Spain ceded the Florida Peninsula. When Mexico achieved its independence, the United States sent Joel Robert Poinsett as its representative to sign a boundary treaty in which the United States tried unsuccessfully to annex the Mexican province of Texas.

Subsequently, a process of peaceful occupation began in which thousands of American immigrants, farmers, and adventurers, began to settle with or without the permission of the Mexican authorities in that region; since 1823, with the permission of the Mexican government, Stephen Austin began to bring Anglo-Saxon immigrants to Texas. On August 25, 1829, Poinsett offered five million dollars for the territory of Texas.

By 1834, the influx of adventurer-mercenaries became even more notorious, such as the signers of the Texas Declaration of Independence, B. T. Archer, and P. B. Dexter, who were wanted for fraud. On March 1, 1836, Texas proclaimed its independence from Mexico and appointed David G. Burnett as president and Lorenzo de Zavala as vice president. After the signing of the Treaty of Velasco (1836), the United States government, which had supported the separatists militarily and economically, rushed to recognize Texas' independence.

For nearly ten years the Mexican government did not try to recover the rebel province but did not recognize its independence. In March 1845, the Republic of Texas was annexed to the United States; the southern border recognized in this annexation was the Nueces River. The annexation caused tensions to grow, which were aggravated when in 1845 the United States government offered to pay the alleged Mexican debt to U.S. settlers if Mexico allowed the United States to buy the territories of Upper California and New Mexico. United States President James K. Polk also ordered General Zacarias Taylor to bring an army to the Texas-Mexico border, which was established in Corpus Christi in August 1845.

In early 1846 Taylor received orders to march with his army south to the Rio Bravo. In March 1846 he took the road to Matamoros, where on April 25, 1846, the Mexican cavalry under the command of General Anastasio Torrejón defeated an American advance force under the command of Captain Thorton. This motive was a good excuse for President Polk to ask Congress to declare war. "American blood had been spilled on American territory. The United States Congress declared war on Mexico on May 13, 1846, as a result of Mexico's "aggressive acts". The distribution of American forces was Taylor in the northeast; Kearney occupied New Mexico and California. Scott initiated a penetration based in the Port of Veracruz and on the Pacific Ocean side, Commodore John D. Sloat.

Successive battles were won by the invaders who advanced triumphantly in the battles of Palo Alto, Resaca de Guerrero or de la Palma, Monterrey, and in February 1847, the famous Battle of La Angostura took place, with which the Mexican Army was able to stop Taylor's advance, But it was not enough, because the Americans, from Veracruz, advanced to Mexico City, under the command of General Scott, continuing their triumphs in San Angel, Churubusco, Padierna, Molino del Rey, Chapultepec and the city's Garitas. The Americans took Mexico City on September 14th and the Mexican government was established in the city of Queretaro.

After the success of the invasion, the United States took advantage of the moments lived by Mexico when its citizens didn't reach an agreement of self-government, however, in the combats that took place, various heroes worthy of mention stood out, such as Generals Nicolas Bravo and Antonio Leon, Colonel Lucas Balderas, Lieutenant Colonel Felipe Santiago Xicotencatl, Captain Margarito Zuazo, the students of the Military School "Niños Héroes" and the heroism of the Irish soldiers who formed the San Patricio Battalion, among others, cannot be excluded. With the signing of the "Treaty of Guadalupe Hidalgo", in February 1848, Mexico lost more than half of its territory and began the withdrawal of the invading troops. On June 15, 1848, this occupation, also called the Mexican American War, finally ended.

War or invasion?

As Howard Zinn, an American historian, quotes in The Other Story of America, the Whig Intelligencer newspaper, the United States invasion of Mexico as "a war between the Anglo-American elite and the Mexican elite". However, he explains that the war was triggered by a circumstantial military incident: the disappearance of U.S. Colonel Cross and the subsequent appearance of his body with a severe blow to the skull. His death was blamed on "Mexican guerrillas", who, by the way, never showed up.

Rio Bravo, the current border between the United States and Mexico, permanently guarded by the U.S. military.
Rio Bravo, the current border between the United States and Mexico, is permanently guarded by the U.S. military. Image: Laizquierdadiario.com

Zinn denounces that "each side competed in encouraging, using, and killing their people. The military campaign of Santa Anna and its allies can be summed up as surrender and retreat. It was the working class and popular sectors who resisted the invasion of the territory and confronted the US army with what they could. This was demonstrated on September 16, 1847, when, despite the courage of men and women who fought until they fainted in the face of the invaders, the United States flag was raised in the Plaza Constitución (better known as the Zócalo) of Mexico City

On the side of the U.S. military, it is known that the soldiers were recruited with promises of an easy military campaign, a few acres of land, and a few dollars. Many were Irish and Germans.

But some voices rose against the invasion, such as that of Frederick Douglas, a freed slave, who wrote in the North Star newspaper: "the present war - wretched, cruel and iniquitous - against our sister republic. Mexico seems to be a scapegoat of Anglo-Saxon greed and love of war". Douglas himself denounced the political party figures of the time, who supposedly opposed the war in the discourse, but even the abolitionists continued to pay their taxes to finance the invasion. Even then, the path of unity between the black community and Hispanics, oppressed by the white, Anglo-Saxon, and Protestant capitalists, was emerging.

A fundamental part of James Polk's political objectives was territorial expansion. Thus, although it was later called the Mexican American War, it was actually a military invasion and subsequent colonization of much of Mexico's territory, key to the United States' capitalist development. Thus, the Republic of Mexico lost approximately 55% of its territory, establishing the borders that are still in force today. In the last clauses of the treaty, the United States committed to pay fifteen million dollars for the ceded territories, in addition to compensation to Mexican citizens of five million pesos.

The Mexican American War of 1846-1848 inaugurated the beginning of a new period in the relations between the two countries. Finally, it is noteworthy that in approximately a decade, both nations would be involved in civil wars, the War of Reform (1858-1861) in Mexico and the War of Secession (1861-1865) in the United States.

Mexican-American War. Image: Currier & Ives : a catalogue raisonné / compiled by Gale Research
Mexican-American War. Image: Currier & Ives: a catalog raisonné / compiled by Gale Research

Surprising Facts about the Mexican-American War

The first major amphibious attack by the U.S. Army

The most important phase of the Mexican-American War began in March 1847, when General Winfield Scott invaded the Mexican city of Veracruz by sea. In what turned out to be the largest amphibious operation in the United States until before World War II. The United States Navy used specially designed surfboats to transport more than 10,000 soldiers to the beach in just five hours. Landings were mostly unopposed by the garrison city outnumbered, which later surrendered after an artillery bombardment and a 20-day siege. Once Veracruz was secured, Scott's army launched the final push of the war: six months later, 265 miles of March clashes until they reached what the gringos called "Los Salones de Montezuma" in Mexico City.

One of the highest casualty rates of any war held by the United States

The United States never lost a major battle during the Mexican American War, but the victory was still costly. Of the 79,000 U.S. soldiers who took part, 13,200 died, a mortality rate of nearly 17 percent, higher than in World War I and World War II. The vast majority were victims of diseases such as dysentery, yellow fever, malaria, and smallpox. According to scholar VJ Cirillo, a greater percentage of U.S. soldiers died from the disease during the Mexican invasion than any war in the United States history. Mexican casualties were also high, with most historians estimating up to 25,000 soldiers and civilians killed. According to the U.S. Department of Veterans Affairs, the last survivor of the conflict, Owen Thomas Edgar, died on September 3, 1929, at the age of 98.

The Battle of Chapultepec "The Legend is Born"

When they arrived in Mexico City in September 1847, U.S. forces found the western route in the capital blocked by Chapultepec Castle, an imposing fortress that was home to Mexico's military academy. General Winfield Scott ordered an artillery bombardment, and on September 13 his troops stormed the Castle's citadel and used the stairs to enter the stone facade. Most of the Mexican defenders soon withdrew, but a group of six teenage cadets remained at their posts and fought to the last minute. According to reports from the battlefield, cadet Juan Escutia prevented the capture of the Mexican flag by wrapping it around his body and jumping to his death outside the castle walls.