When Texas won its independence in 1836, the US and Mexican governments fought politically over the status of the new Republic of Texas. France, the United States and Iberia had already recognized it, while Mexico, Britain, Russia, and Austria all refused to recognize the state. The Americans had also made very powerful pushes west, in a spirit they called Manifest Destiny, and they were threatening Mexico's land. The Mexican government of Antonio Lopez de Santa Anna clung to power by a slim thread as his political enemies gained ground, and he needed a scapegoat by which his government could hold onto power. He decided to turn his country's anger towards the expansive Americans.
The United States seemed to many in Mexico an imminent threat, so much so that Santa Anna, whose country was on the brink of civil war, decided to paint the Americans as expansive beasts. Meanwhile, in America, the Mexicans seemed to be a nuisance in the South West that blocked America's standing dream of controlling land from "sea to shining sea," and that therefore many in Congress, and especially in their relations with Texas. To America, many saw it that all they had to do was fight a war with Mexico, and that it would be sufficient for connecting the country. While Mexico was clearly weakening, Santa Anna still kept a standing army to maintain order, while the American Army was undergoing a deep era of military reform that integrated the new system of railroads into the developing system. While America's military looked towards the future, the military of Mexico stagnated, as training quality decreased, foreign weapon suppliers could not be paid, and the Mexican government filled itself with corruption.
Another big source of conflict was California, although it was owned by Mexico, it had been populated by Americans, and was swaying towards annexation by popular opinion to the US. The Mexicans could simply not keep a cap on the American immigration, and the independence and annexation movements they caused. Tensions continued to increase between the two sides as the American settlers clashed with the Mexican authorities that ran the territory. But while tensions rose in the west, in Texas, relations reached a heating point betweent the three main states vying for control, the United States, the United Mexican States, and the Republic of Texas. In 1845, Texas was annexed by the United States, and Mexico demanded the Americans relinquish their hold on Texas, when neither side backed down, Mexico declared war.
California CampaignJohn C. Fremont, who had been in command of many expeditions to California, was put in command of the 10,000-man Army of California. He marched his army into the center of California, marching south of the Sierra Nevada Mountains, and through the north Mojave Desert, and then began to move south to the sea. They find combat with 125 Mexicans garrisoning the town of San Bernardino, suffering only five deaths and 20 wounded men, all of the Mexicans are killed or captured. The town of Los Angeles, occupied by 2,400 Mexican soldiers, was attacked on March 12, 1846, and after twwo days of battle, the Mexican settlement was captured, and all of its defenders had been captured. Only 18 Mexicans were killed, 200 were wounded, to the 12 Americans killed, and 130 wounded. The Battle of Los Angeles ended up with the Mexican governor of the territory withdrawing all Mexican forces north of the San Joaquin River, giving Fremont the ability to exercise his role as governor and declaring the California Republic on April 7.
The American forces begin moving again in May 1846, accompanied by the California Regiment, a group of 1,500 miltiamen that will help him fight the Mexicans, and to act as the army of the new republic. The Americans arrive at Monterey on at Monterey, finding it has been heavily fortified by 5,000 Mexican troops, the Americans launch artillery on the city, and three US warships then land 450 US Marines behind enemy lines. The Mexicans are beaten to dust, 750 die, 800 are wounded, and the rest are captured when the battle ends on September 1846. San Jose and San Francisco are captured easily, and almost without a fight, and the small town of Sacramento, where the Mexican governor was staying, is captured on December 14, 1846, and the Mexican's officially surrender California as of January 5, 1847.
Yucatan Campaign and Baja Campaign
The Americans landed 12,000 soldiers on the Yucatan peninsula, all across the Yucatan's northern coast, mainly at Cancun, where they then march along the coast, commanded by Winfield Scott. They captured Playa de Carmen without a fight, and then marched west to Valladolid, defended only by 200 Mexicans, and then marched north for a siege of the city of Merida. Merida was defended by only 1,400 soldiers, but fell to the American siege after just 12 days. After this there was very little resistance until they reached the town of Campeche, defended by 2500 Mexicans. The Americans attacked the town in three waves, one consisting of 4,000, another consisting of 3000, and a final reserve wave consisting of 3000 more soldiers. The first wave engaged the Mexicans, but the Mexicans got 2000 re-inforcements before the battle began, and the second wave was called in for a flanking attack, which was then largely engaged by the Mexicans. The third wave marched around the enemies rear, where they then outmaneuvered the Mexicans, forcing all the remaining Mexicans to surrender.
In May 1847, Stephen W. Kearny lead an army of 8000 American soldiers to conquer the Baja Peninsula for the US. He encountered 400 Mexicans immediately after entering the peninsula, but quickely brushed them off after only taking 20 casualties, allowing him to capture Tijuana and Mexicali. He then continued south to San Carlos, where he encountered very little or no resistance has his army marched south and miles into the Baja. But they eventually encountered resistance at the Battle of Mulege, where 24 Mexican guerrillas fought the Americans, killing four of them, but ultimately being forced to surrender the town. La Paz, which the Americans attacked on March 8, 1848, was defended by 2000 Mexicans and the Americans were able to surround the city, and after a short, three-week, siege, the Mexicans surrendered, and the Americans now had control over the Gulf of California.
Northern Mexico Campaign
With California, the Baja, and the Yucatan subjugated, the US high command decided that it was time to invade Mexico proper. 25,000 American troops marched from Texas into the Mexican provinces of Neuvo Leon and Coahuila, lead by General Sterling Price. The main objective was Monterrey, but unlike the previous American campaigns Mexico was heavily defended and their forces lead by Mexican general, Antonio Lopez de Santa Anna. His plan was to conquer Coahuila, and then march south to Monterrey, hoping to bypass the Mexican army in that province. Zaragoza was the first town to put up any resistance, 200 Mexicans fought an American battalion of 300, but were defeated after two hours of fighting. Muzquiz was then assaulted by two American regiments, consisting of 3000 men in total, and fought over for ten hours until the city's 450 defenders all surrendered. The entire army then marched south to the city of Monclova, defended by 2000 Mexican troops, it posed a true challenge to the Americans. US forces assaulted the city on May 4, 1848, and captured after a two day siege. They then marched south to Saltillo, the capital of Saltillo, but found it undefended. A later search found a Mexican order from Santa Anna himself that all Mexican troops retreat out of Coahuila and into Neuvo Leon to defend Monterrey.
The Americans then marched by the Mexican roads from Saltillo east towards towards Monterrey, meeting no resistance, and linking up with another American army lead by Zachary Taylor that had been marching through Neuvo Leon, and the combined army now had 40,000 men to assault Monterrey. Monterrey had been defended by 20,000 Mexican troops, along with artillery and cavalry, but was eventually surrounded and attacked on July 7, 1848. The Americans were forced to move into the city on July 10, where they met powerful Mexican resistance, from both soldiers and armed civilians. The Americans lost 500 men in the battle, until the Mexicans finally surrendered on July 20, but Santa Anna had already escaped the city. The Americans now controlled northern Mexico, as American forces had already captured Chihuahua and Sonora, and now the Americans were marching south and deep into Mexico.
Mexico City Campaign
An American army of 12,000 lead by general Winfield Scott landed at the Mexican port of Veracruz, which had been defended by 3,000 men of the Mexican Army. The Americans laid siege to the city on March 9, attacking by land and sea, but the Americans had the advantage of numbers, and the city fell to the US forces on March 14. They then marched for 3 days from Veracruz to the city of Puebla, which was then taken without firing a shot, as it had only been defended by 200 Mexicans. American forces then continued to march from their positions in Puebla to attack the enemy capital, Mexico City.
The Americans combined army of 48,000 men surrounded Mexico City, defended by 40,000 Mexican soldiers. The Mexicans were all pushed into the city, where a lengthy siege then began on May 8, 1848, and American artillery was moved into position, bombarding the city constantly. Santa Anna was almost driven mad by the chaos, as his defenses were destroyed by American artillery and many of his people began rioting in the streets as protest to the war. American soldiers finally breached the city on May 31, and then proceeded to surge into the city, with little resistance by the city's defender or its native population. It was within the city that heavy street-to-street fighting broke out, and then that the Americans began to take significant casualties.
Mexican soldiers defended their capital city with their lives, even though they had surrendered in large swathes by now, they still put up a stiff resistance. Mexican citizens took to private arms as the Americans attack deeper into the city, and then moved forward towards the Chapultepec Castle. But despite the castles defenses, the United States Marine Corp charged the castle, and took it within one day's time. A young American officer, Ulysses S. Grant, lead a unit of infantry that attack the remaining gates of the city, and won himself a hero's honor in taking them. When the fighting finally ended, on July 4, 1849, the war ended with Santa Anna's official surrender, and a ceasefire was declared later that day. With the war apparently over, the American soldiers returned home, and the Mexican people began to rebuild their shattered nation.
Treaty of Guadalupe Hidalgo
The Treaty of Guadalupe Hidalgo was signed between the interim military government of Mexico, and an American peace delegation on February 2, 1849. While two versions had been proposed, one by Southern congressmen calling for a minimal annexation, Northern delegates to Congress eventually won out and their version, which allowed for more annexation, was the version signed. The peace treaty had been mediated by a French representative, and the terms were as follows:
- Alta California, Baja California and Baja California Sur, New Mexico, and most of Sonora, Chihuahua, Cohuila, and Neuvo Leon will be turned over to the United States government
- Mexico shall pay ten million pesos to the United States
- Mexico will recognize the US annexation of Texas
The Mexican government was barely able to the reparations, and the Mexican economy subsequently collapsed the next year, eventually leading to an alliance of the clergy, conservatives, and landowners taking control and re-instating the monarchy under Agustín's heir, Agustín Jerónimo, so as to try and prevent another republican-backed takeover by a character such as Santa Anna.
All of the territories gained from Mexico were put under temporary military control, but California wouldn't last like that too long. On November 12, 1849, gold was discovered at Sutter's Mill, and the California Gold Rush began, and the miners heading west were named 49er's after the year the gold rush began. California's population boomed from 90,000 in 1850, to almost 380,000 by 1860. This compelled the US government to give California statehood on September 9, 1851. The acquiring of the Mexican provinces allowed the US to build naval bases on the Pacific Ocean, and allowing the US to extend its new-found power to the Pacific Ocean. The US was now the only world power existing in North America, Mexico was in an economic collapse, and Canada was now only just a trading company for the British. And when construction began on the Transcontinental Railroad in 1863, it was made to extend to both California, and to Guaymas.
Each of the new territories were given the choice of being a slave or free state upon admission to the Union, as per the Missouri Act of 1821, resulting in each state being admitted as a free state. This overwhelming power of the Free states, combining with the high power of federalism in the North resulted in the 13th Amendment to United States Constitution, officially banning slavery, in 1856. The success of the amendment was much owed to the new Republican Party, which was founded in 1850, and lead by John C. Fremont, elected to the presidency in 1852.