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Borderlands: 1848 War With Mexico Created Southwest 18 (1999)

A unique resource of faculty edited college student articles on the history and culture of the El Paso, Juárez, and Southern New Mexico regions.

1848 War With Mexico Created Southwest

Article first published in Vol. 18, 1999.

By Regina Prieto, Lisa K. Ordaz, Araceli Navarrete, Antonio Ruiz, Susana Urrutia, Bassam Abdelfattah, Veronica Zamora and Ruben Rios

In 1998, the United States celebrated the 150th anniversary of the Treaty of Guadalupe Hidalgo, which ended the war with Mexico fought between 1846-1848. The treaty is one of many the United States negotiated during the 1800s but is today forgotten or taken for granted. Mexico lost two-fifths of its land and the U.S. completed its move westward to the Pacific Ocean. Both the war and the treaty greatly affected huge sections of the Southwest, changing geography and history.

The war closely followed the annexation of Texas in 1845. When Texas was part of Mexico, the United States made various attempts to buy it. In 1827, President John Quincy Adams offered to buy Texas from Mexico for $1 million, an offer that Mexico rejected. Andrew Jackson tried again in 1829, offering $5 million, but Mexico still refused to sell her territory.


Image caption: Map of the United States Southwest

By the fall of 1835, Texas was at war with Mexico to gain its independence. After various encounters with Mexican troops, Texas declared its independence from Mexico on March 2, 1836, declaring its boundary to be the Rio Grande. Although the Texans had lost the Battle of the Alamo the previous month, the Texans surprised the Mexican army at the Battle of San Jacinto on April 21, 1836, handily defeating it.

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The victors took the army's leader, General Antonio Lopez de Santa Anna, prisoner. He signed the Treaty of Velasco, granting Texas independence and recognizing the Rio Grande as the boundary between Texas and Mexico. As soon as he was free, Santa Anna, who was also President, repudiated the treaty. Mexico only recognized the Nueces River, north of the Rio Grande, as the boundary.

Texas remained an independent republic for almost a decade. Although Texas formally asked to become part of the United States, the American government hesitated. Mexico had made it clear that annexing Texas to the Union would be equivalent to the declaration of war. But on December 29, 1845, President John Tyler signed the bill to admit Texas to the Union as the last act of his administration. Mexico broke relations with the United States.

James K. Polk, who had strongly advocated annexation of Texas and expansionism in general, followed Tyler as President. Polk sent John Slidell, Minister of Mexico, to negotiate, offering to cancel a series of debts if Mexico recognized the Rio Grande as the border between the two countries. Slidell also tried to buy the territories of New Mexico and California.

In turn, Mexico asked the United States to reconsider annexing Texas if it admitted Slidell to negotiations. The United States refused, Mexico declined to talk with Slidell, and Polk ordered troops to the disputed border.

General Zachary Taylor with 4,000 men arrived near Corpus Christi along the Rio Grande in late January 1846. The Mexicans regarded it as an invasion of their territory and threatened to attack if the United States did not remove its troops.

The American troops stayed along the mouth of the Rio Grande, waiting for Mexico to begin hostilities to initiate the war. In April 1846, during a small encounter between American and Mexican troops, several American soldiers were killed. President Polk convened Congress and announced: "American blood has been shed on American soil." The United States officially declared war on Mexico on May 13, 1846. 

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The war lasted two years with the Mexican Army suffering huge losses. General Zachary Taylor's forces moved south from Texas to capture Monterrey. On February 22, 1847, Taylor's troops marched from Monterrey to Buena Vista and defeated Santa Anna's men, who outnumbered the American force three to one. This victory made General Taylor famous and helped him become the President of the United States in 1849.

From the east, General Stephen W. Kearny seized New Mexico and California. Colonel Doniphan, after helping Kearny capture Santa Fe, moved south and secured northern Mexico. On another front, General Winfield Scott arrived in Veracruz just outside the Mexican capital, taking the city after four days of fighting. Scott then prepared to march on Mexico City. On September 13, 1947, Scott's troops attacked the capital, leaving 4,000 Mexican soldiers dead with another 3,000 taken prisoner.

In one poignant fight at the Castle of Chapultepec, a group of young Mexican cadets committed suicide rather than surrender their country's flag to the Americans. To this day, Mexicans pay homage on September 13 to the niños heroes, who chose to die for their country. With this battle, the war ended.

During the war, Mexico's unstable government had changed hands several times. The government went from a federal constitution to a centralized dictatorship. Treaty negotiations had to be postponed until a temporary president, Manuel de la Peña, could take power. Finally, on February 2, 1848, at Villa Guadalupe Hidalgo, north of Mexico City, American and Mexican commissioners signed a treaty to establish peace between the two countries.

According to the terms, Mexico recognized the Rio Grande as the boundary between the United States and Mexico. It ceded the territories of New Mexico and California to the United States, and in turn, the United States agreed to pay $15 million dollars and forgive Mexico's debts.

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The United States added more than 525,000 square miles of land that would become the states of New Mexico, Arizona, California, Nevada, Utah, Colorado and part of Wyoming. They also took complete control of what is now Texas. Besides land, the United States gained about 80,000 people living in these areas; only about 2,000 people chose to remain Mexican citizens.

Besides land, the Southwest yielded gold, discovered in California in 1849, silver in Nevada and New Mexico, copper in Utah, Arizona and New Mexico, oil and natural gas in Texas and other states, uranium in New Mexico and other natural resources.

Historian Neil Magnum says that Mexico's pride was greatly damaged and the country felt both trauma and humiliation, leaving a lasting scar on relations between the two countries. Although Mexico fought bravely, it lost every battle.

In their book The Mexican War: Changing Interpretations,  historians Odie B. Faulk and Joseph Stout say that Mexicans became unhappy with their government and began to distrust Americans. They feared and hated the "gringos," as they called Americans. As the land the United States won became more populated, conflict increased between Anglo settlers and former Mexican citizens. Oscar Martinez says simply, life on the border involved a complicated balance of diverse cultures and interests. The ugly head of racial discrimination became a problem on the border, according to Martinez. The new "Mexican-Americans became a 'subordinate minority' and had to endure ethnic tensions that often escalated into violence."

By no means was the conflict between Mexico and the United States over. Because of inaccuracies in mapping the new boundaries and a desire for a southern route for a transcontinental railroad, the United States would once again try to purchase Mexican territory. Just a few years later, Mexico would sell more land under the Gadsden Treaty to its land-hungry neighbor.

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