February, 1848: Treaty of Guadalupe Hidalgo Summary

  • Last updated on November 11, 2022

The Treaty of Guadalupe Hidalgo, drafted and signed at the Mexican village of Guadalupe Hidalgo, near Mexico City, ended the Mexican War. The war had been prompted partly by hawkish adherents of manifest destiny, a belief in the inevitable expansion of the United States through the whole of North America, although it had nominally erupted over disputed territories shortly after the United States annexed the Republic of Texas in 1845. The specific cause of the war was the dispute over which river— the Rio Bravo del Norte or the Nueces—marked a boundary line between the two countries. War had been declared formally in April of 1846, after Mexican and U.S. troops clashed in the disputed territory between the two rivers.

The Treaty of Guadalupe Hidalgo, drafted and signed at the Mexican village of Guadalupe Hidalgo, near Mexico City, ended the Mexican War. The war had been prompted partly by hawkish adherents of manifest destiny, a belief in the inevitable expansion of the United States through the whole of North America, although it had nominally erupted over disputed territories shortly after the United States annexed the Republic of Texas in 1845. The specific cause of the war was the dispute over which river— the Rio Bravo del Norte or the Nueces—marked a boundary line between the two countries. War had been declared formally in April of 1846, after Mexican and U.S. troops clashed in the disputed territory between the two rivers.

The U.S. Victory

In Mexico, political turmoil and poor military strategy and preparedness at first led to fairly easy U.S. victories. Successful campaigns in northeastern Mexico by General Zachary Taylor caused the collapse of the Mexican government and the recall from exile of General Antonio López de Santa Anna, who fought a close but losing battle against Taylor at Buena Vista in February of 1847. The tide turned fully against Mexico when General Winfield Scott invaded Mexico at Veracruz and fought his way inland against tough resistance to capture Mexico City. The crucial battle in Scott’s march from the sea was fought against Santa Anna at Cerro Gordo on April 18, 1847. Even with Santa Anna’s defeat, Scott’s army had difficulty, and it was not until September 14, 1847, that his troops entered and took control of the Mexican capital.

Santa Anna, threatened with impeachment for his conduct of the war, went once more into exile. In order to take direct command of the Mexican forces, he earlier had named Manuel de la Peña y Peña interim president and eventually had to ask the Peña government for permission to leave Mexico. It was Peña who was forced to agree to the terms of the Treaty of Guadalupe Hidalgo, negotiated under the weakest possible conditions for Mexico. For a payment of $15 million and $3.25 million in claims of Mexican citizens, Mexico ceded to the United States the territories of New Mexico and Upper California. The agreement also established the Mexican-American boundary, which followed the course of the Rio Grande from the Gulf of Mexico to the southern border of New Mexico, west to the Gila and Colorado Rivers, and eventually to a point just south of San Diego on the Pacific Ocean.

Negotiations

The negotiations leading up to the treaty were complex. In April of 1847, President Polk had sent Nicholas P. Trist of the Department of State to Scott’s camp with a secret treaty proposal drafted by Secretary of State James Buchanan. Trist was empowered to consider counterproposals and secure an armistice, which was actually arranged in late August of that same year. Scott had been in secret communication with Santa Anna, who, without the knowledge of the Mexican government, was trying to arrange treaty terms on his own. Santa Anna assured Scott that hostilities could be suspended and a treaty negotiated if and when Scott’s army laid siege to Mexico City. Scott had even written a memorandum in which he avowed that he would fight a battle in view of the capital and then “give those in the City an opportunity to save the capital by making a peace.”

General Scott’s troops storming Molino del Rey, while advancing toward Mexico City. (Institute of Texan Cultures)

Scott, with victories at Contreras and Churubusco in August, 1847, had met Santa Anna’s conditions. The road to Mexico City was open, and the remnants of Santa Anna’s army had been put to disordered flight, taking refuge within the capital. Scott was certain that a peace with a compliant Santa Anna could be quickly negotiated. Santa Anna, however, was as deceitful and crafty as Scott was forthright and naïve. He knew that Scott’s army was wracked by disease, declining morale, and logistics problems, and he believed that time was an invisible ally. As his blame-shifting maneuvers made clear, he also wanted to avoid making any treaty concessions that would tarnish his national image. Thus, although a cease-fire was arranged and agreed to, the efforts to draft a mutually acceptable set of terms at the ensuing peace conference proved futile and were probably doomed from the outset. The armistice broke off on September 6, and on September 14 Scott took Mexico City. Santa Anna soon fled.

When it became clear to Buchanan and Polk that Santa Anna was stalling, Polk ordered the recall of Trist, in part to counteract the impression that the United States was anxious to achieve a peace, a view gaining currency among the Mexican people. Trist did not return, however; he stayed on after the futile negotiations broke off and fighting resumed. The war dragged on past the departure of Santa Anna, who met his final defeat at Puebla on October 11. It was abundantly clear that Mexico could not turn the war’s tide, and within two months, it sued for peace. Trist, never having returned home, became the chief U.S. negotiator at Guadalupe Hidalgo, where the treaty was finally signed.

General Winfield Scott’s entry into Mexico City completed the American victory. (Library of Congress)

Terms

The drafted terms, readied by January 24, 1848, more fully realized the territorial ambitions of the United States than the terms that had been discussed during the earlier armistice conference, which had at least left the Texas border question open. However, even from the outset of the earlier negotiations, it had been clear that the United States was determined to annex both Upper California and New Mexico. In the end, Santa Anna’s delaying tactics had proved a bit more costly to Mexico.

Because a flawed map was used during the treaty negotiations, the boundaries between Mexico and the United States remained open to interpretation. Surveyors could not agree on the identity of the first branch of the Gila River, one of the important demarcation lines, and the boundary line between Mexico and the United States in the area separating the Gila River and the Rio Grande was not settled. However, both the Rio Grande and the Gila River were established as principal boundaries. Mexico thereby ceded territories south of the Nueces River and all of Upper California from one nautical league south of San Diego to the Northwest Territories. The United States gained all of the Territory of New Mexico, the disputed lands in southern Texas, and Upper California. In consideration for ceding this vast acreage, the United States was to pay only the stipulated $15 million plus the $3.25 million in claims. It was a grand bargain for the expansionist believers in manifest destiny. The treaty terms were quickly accepted by Polk and, with some amendments, ratified by the U.S. Senate on March 10, 1848.

Aftermath

The Treaty of Guadalupe Hidalgo did not immediately end the boundary issue. In 1853, during the administration of Franklin Pierce, the current border between Mexico and the United States was finally set when the United States purchased the Arizona Territory from Mexico in the Gadsden Purchase and described the boundary line between the two countries in the disputed area.

An important provision of that treaty, Article VII, granted U.S. citizenship with full constitutional rights to the Mexicans living in the ceded territories and guaranteed them ownership of their land. However, through the invalidation of Spanish and Mexican land grants, federal courts and the U.S. Congress allowed government agencies, ranchers, land speculators, and business and railroad magnates to gobble up acreage that, by the terms of the treaty, rightly belonged to Mexican Americans. Over two generations, almost twenty million acres of their land was lost to private owners and state and federal agencies.

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