Causes and Consequences of the U.S.-Mexican War (1846-1848)

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            The Mexican-American war as was popularly known was basically an armed war between the United States and Mexico which lasted for a period of two years that is from 1846 to 1848. The war begun when the U.S wanted to take possession of the Texas state but Mexico claimed the ownership of Texas as a secede province and refused to recognize the U.S’s secession program. Various terms have been used to describe this kind of war. In U.S, it is referred to as the Mexican war and rarely as the US-Mexican war but in Mexico it is known as the North America intervention in Mexico, American Invasion of Mexico and as The War of ’47. Mexico gained independence from Spain in 1821 which inherited various states from Spain Empire including Texas (Zinn 59.)  Because it wanted to control the border region of Texas, it allowed few U.S people to settle there as the state initially had few people settling there. The region later had an influx of the U.S citizens to a scale not expected by Mexico and the English language dominated there.

            The U.S government made efforts to buy Texas State but the Emperor by the time Agustín Iturbide and also his successor Antonio Lopez refused as they wanted to colonize its northern provinces. By this time Texas had become disheartened with Mexican government where many Mexican soldiers in Texas were convicted criminals who had the option of either serving in the army or be imprisoned. Texas revolution emerged in 1836 when it declared independence from Mexico but only to be raided later by Mexico again. Texas later on defeated the Mexican Emperor who was held captive by the Texas militias only to be released after signing the Velasco treaty where Rio Grande was to be recognized as the boundary between Texas and Mexico. The Mexican government refused to honour such treaty as the Emperor made the decision in his own capacity and not for the whole state (Brinkley121). Later on Texas laid diplomatic ties with Britain, France and the U.S as a sovereign state. During this time, the people of Texas wanted the state to be annexed by the U.S but the U.S president of the time Andrew Jackson refused.

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            Under U.S president John Tyler, he accepted it but as a slave state. The bill was later signed into law in March 1845 and ratified by Texas in December 29th 1845 as the 28th state. Mexico had earlier on warned that annexation of Texas would mean war with the U.S but Britain and on seeing that Texas was an independent state, intervened to stop Mexico from declaring the war but did not succeed in the process of intervention. The contentious issue was also the boundary of Oregon between Mexico and Texas. The diplomatic ties between Mexico and the U.S worsened when Texas was granted the statehood in 1845. The U.S helped Texas to claim the land north of Rio Grande which provoked a dispute with Mexico. In June1845, the U.S president James Polk sent General Zachary Taylor to Texas and by October, 3,500 Americans were on river Nueces to defend Texas from Mexico’s invasion. The U.S president wanted to protect the border where he had instructed the Pacific naval to grab California ports in case Mexico declared war. He also wrote to Thomas Larkin who was an American consul in Monterey to ensure a peaceful takeover of California. In 1845 to 1846, federally commissioned explorer John Fremont and other armed men entered California but the Mexican authorities were alarmed and ordered for their leave.

            In November 1845, the president again dispatched John Slidell who was a secret representative to Mexico with an offer of twenty five million dollars for the Rio Grande border in Texas and Mexico’s provinces of Alta California and Santa Fe de Nuevo Mexico. During this time, Mexico was not in a position to negotiate. In 1846, the presidency changed hands four times, the war ministries six times, and finance ministry sixteen times. At this point, the Mexicans who opposed the annexation process, unleashed terror to U.S including the then president of Mexico Jose Joaquin de Herrera who were seen as traitors. Military opponents to Jose’s force supported by populist newspapers viewed Slidell’s presence in Mexico City as an insult. Due to this, Jose Joaquin was accused of treason and deposed.

            Under the leadership of Mexico’s General Mariano Paredes, his government reaffirmed Mexico’s position to claim Texas and it is here that Slidell was convinced that Mexico should be chastised and returned to U.S. Thereafter, the US president ordered General Taylor and his forces south to the Rio Grande, invaded the territory that Mexicans claimed as their own. In April 1846, Mexican’s sturdy cavalry attacked the U.S’s sixty three-man patrol that had been sent into the disputed territory. It killed eleven U.S soldiers which later came to be known as the Thornton affair after the slain U.S officer who was in command. The U.S president had already heard about this Thornton affair and sent his message to the Congress that Mexico had passed the boundary of the U.S and invaded its territory. It was from the president’s message that the Congress approved the declaration of war with the southern democrats in strong support as they saw annexation of Mexico would have increased the number of slave states to the U.S. The Congress declared war on Mexico in May 1846 while Mexico’s Congress declared war in July 1846. During this time Antonio Lopez wrote to Mexico City that he no longer had aspirations to the presidency but would use his military experience to fight off the U.S forces. The then president Valentín Gomez was desperate and accepted the offer where Santa returned. He had secretly dealt with representatives of the U.S where he pledged that if were allowed back to Mexico through the U.S naval blockades would sell the contested land to U.S at a reasonable amount. Once back in Mexico, he did not fulfill his promise instead he declared himself president again and fought the U.S troops unsuccessfully.

            In the U.S some people were against the war. People like Joshua Giddings led a group of dissenters in Washington D.C and termed the war as an aggressive, unholy and unjust one and voted against supplying soldiers and weapons. Abraham Lincoln also demanded to know the causes for the war and be shown exactly where Thornton had been attacked and the U.S bloodshed. During the war period, there were innovations such as the telegraph which provided communication means to people. That is people received updated information from the reporters who were available at the war scene. This was the first time in the history of America where the information from the press people but not the opinions of politicians that caused large influence in shaping the people’s minds and attitudes towards the war and whenever the war news was released, it instilled extraordinary popular excitement in people.

Through these constant reports from the battlefield, Americans were emotionally united as a community. The victory of Zachary Taylor at Palo Alto, caused people to turn up in large numbers in the town of Lowell, Massachusetts. Mexico had desertion problems where most its forces were finished on the eve of the battle. This is because most of its soldiers were peasants and were loyal to their families than their generals. Most of them were hungry, not paid well and under equipped. For the U.S, the desertion rate was low about 8.3 percent compared to Mexico’s 12.7 percent (Ian & Coll 112) In the U.S, they deserted to join other U.S units while others left due to miserable conditions in the camp and were using the army to get free commutation to California. The U.S president later on sent General Winfield Scott to port of Veracruz by sea to begin invasion of the heartland of Mexico.

In May that year, Scott and his troops went further up to Puebla the second largest city in Mexico and because of citizen’s hostility to Santa Anna, the city capitulated without resistance. Mexico was under full control of the U.S forces after the battle of Chapultepec and because of this Scott became an American national hero after the victory in the Mexican-American war. He later became the military governor of the occupied Mexico City.  After obtaining full control of Mexico City, the Treaty of Guadalupe Hidalgo was signed in February 1848 by the American diplomat Nicholas Trist and this ended the war and gave U.S consent to take full control of Texas. It also established the U.S-Mexico border of Rio Grande River. The Mexico in return received 18.25 million U.S dollars which were less than the initial amount the U.S wanted to give Mexico. Also the U.S decided to write off Mexico’s debt of 3.25 million U.S dollars.

            Before the ratification of this treaty, the U.S senate made two modifications by changing the language of the Article IX which guaranteed the Mexican civilians living in purchased land the right to become U.S citizens. It removed Article X which provides the legality of land grants made by the Mexican government. In May 1848, the two nations exchanged the ratifications of the treaty but agreed further to a three- article protocol known as the Queretaro protocol to explain the amendments. The first one claimed that the original Article IX although replaced by Article III of Louisiana treaty still conferred rights delineated in the original article. The second article confirmed the legality of land grants pursuant to Mexican law and the protocol was finally signed in Queretaro by Sevier, A.H, Nathan Clifford and Luis de la Rosa.

            The consequences of the war were felt by both nations. In Mexico, more than five hundred thousand square miles of land lost to the U.S. The annexed had been occupied by about one thousand Mexican families in Alta California and seven thousand in Nuevo Mexico. Few of these relocated further north in Mexico but majority remained in U.S as slaves. In Mexico City, the Chapultepec Park was created to commemorate the death of the six junior military cadets who fought to their death rather than surrender to U.S forces.  During the war, thirteen thousand U.S soldiers died, where one thousand seven hundred were killed in combat but the rest died due to diseases such as yellow fever. In the exercise, innocent civilians were scalped, women were raped and murdered, children killed, homes were burned down and also Catholic religious objects and buildings were despoiled (John 129).

            In the U.S, the president was under sharp criticism from the house of the Representatives and this impacted negatively in his political career and even the Democrats lost to Representatives.  The acquisition of new land gave in a surge of loyalty in citizens who believed in their nation’s apparent destiny. Also the army swelled from six thousand to more than one hundred and fifteen thousand which strained the budget of the U.S to certain extent. From this, 1.5% were killed in the fight, 10% died of diseases and another 12% were left wounded or discharged because of diseases or both. After the end of this war several centuries ago, the war veterans still suffer from the diseases contracted during the campaigns and the causality rate by the time was over 25% for the seventeen months of war. Also during the war, there were various divisions in U.S regarding the disposition of the conquered Mexico which was a setback to the countries development.

            The war in Iraq and Afghanistan is just a repetition of what U.S did to Mexico where the president of the day enjoys the powers he possesses to stage an attack to a country that is not in good terms with it. He only needs the approval of the members of the house whether he is on side of Congress or Representatives to declare a war on another country. The war of U.S in Iraq received protests all over the world including the UN’s Security Council but U.S went on with its plans. Several lives have been lost and are still being lost in Iraq and Afghanistan with uncountable loss of property due to the insurgence of Islamic militias who are against the presence of foreign forces including the U.S in their territories.

Works cited

Zinn, H. A Peoples History of the United States from1492 to Present. 2008.

Brinkley, A. American History to 1877. (12th Edition), Vol. 1.

Arthur, S. Dueling Eagles: Reinterpreting the U.S.-Mexican War, 1846–1848. 2004

John, C. Anti-Catholic Sentiment among American Soldiers in the U.S.-Mexican War. Blackwell             Publishing, 2004.Vol. 35 Issue 2. PP 129 – 152.

Ian B. & Coll, F. The task of the Rangers in Texas in the US-Mexican War, 1846- 1848. 2003.

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Causes and Consequences of the U.S.-Mexican War (1846-1848). (2016, Aug 26). Retrieved from

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