The Mexican-American battle (1846-1848) marked the very first U.S. Armed conflict chiefly dealt with on international soil. It pitted a politically divided and militarily unprepared Mexico against the expansionist-minded administration of U.S. President James K. Polk, who thought the joined States had a “manifest destiny” come spread across the continent to the Pacific Ocean. A border skirmish along the Rio Grande began off the fighting and was complied with by a collection of U.S. Victories. As soon as the dust cleared, Mexico had actually lost about one-third of its territory, including nearly all of present-day California, Utah, Nevada, Arizona and new Mexico.

You are watching: What was the immediate cause of the mexican american war

Causes of the Mexican-American battle

Texas got its self-reliance from Mexico in 1836. Initially, the unified States decreased to incorporate it right into the union, largely due to the fact that northern politics interests were versus the enhancement of a new slave state. The Mexican government was likewise encouraging border raids and warning that any type of attempt at annexation would bring about war.

Did friend know? gold was discovered in California just days before Mexico ceded the land come the United says in the treaty of Guadalupe Hidalgo.

Nonetheless, addition procedures were easily initiated after ~ the 1844 choice of Polk, who campaigned that Texas should be “re-annexed” and also that the Oregon Territory should be “re-occupied.” Polk also had his eyes on California, new Mexico and also the remainder of what is this day the U.S. Southwest. Once his market to acquisition those lands to be rejected, the instigated a hit by moving troops into a discussed zone in between the Rio Grande and also Nueces River the both nations had previously known as part of the mexican state of Coahuila.


On April 25, 1846, mexican cavalry assaulted a group of U.S. Soldiers in the disputed zone under the command of general Zachary Taylor, killing about a dozen. They then laid siege come an American fort along the Rio Grande. Taylor dubbed in reinforcements, and–with the assist of remarkable rifles and also artillery–was able to defeat the mexicans at the war of Palo Alto and Resaca de la Palma.

Following those battles, Polk told the U.S. Congress that the “cup the forbearance has been exhausted, even before Mexico pass the border of the united States, invaded our territory, and also shed American blood upon American soil.” 2 days later, on might 13, Congress asserted war, regardless of opposition from some north lawmakers. No official declaration of war ever came native Mexico.

Mexican-American War: U.S. Army advances Into Mexico

At that time, only around 75,000 mexican citizens live north of the Rio Grande. As a result, U.S. Pressures led by Col. Stephen W. Kearny and Commodore Robert F. Stockton to be able to overcome those lands through minimal resistance. Taylor an in similar way had tiny trouble advancing, and he captured Monterrey in September.

With the losses adding up, Mexico turned to old standby basic Antonio López de Santa Anna, the charismatic strongman who had actually been life in exile in Cuba. Santa Anna persuaded Polk that, if allowed to go back to Mexico, the would finish the war on terms favorable come the united States. However when the arrived, he automatically double-crossed Polk through taking regulate of the mexican army and leading it into battle. In ~ the fight of Buena Vista in February 1847, Santa Anna suffered hefty casualties and also was compelled to withdraw. Regardless of the loss, that assumed the mexican presidency the complying with month.

Meanwhile, U.S. Troops led by Gen. Winfield Scott landed in Veracruz and also took end the city. Castle then started marching towards Mexico City, essentially following the same path that Hernán Cortés followed when he invaded the Aztec empire. The Mexicans withstood at Cerro Gordo and also elsewhere, however were bested each time. In September 1847, Scott successfully laid siege come Mexico City’s Chapultepec Castle. Throughout that clash, a group of army school cadets–the so-called niños héroes–purportedly committed suicide quite than surrender.

See more: Why Is The Intrapleural Pressure Negative Rather Than Positive?

Treaty of Guadalupe Hidalgo ends the Mexican-American war

Guerilla attacks against U.S. Supply lines continued, however for every intents and also purposes the war had ended. Santa Anna resigned, and also the United claims waited for a new government qualified of negotiation to form. Finally, ~ above Feb. 2, 1848, the contract of Guadalupe Hidalgo was signed, developing the Rio Grande and also not the Nueces River as the U.S.-Mexican border. Under the treaty, Mexico also recognized the U.S. Annexation of Texas, and agreed to offer California and also the remainder of its region north that the Rio Grande for $15 million plus the presumption of details damages claims.