American-Mexican War (Napoleon's World)
Timeline: Napoleon's World
Date September 14, 1839-1845
Location Northern and Central Mexico, South Central and Western United States
Result American Victory

US flag 48 stars United States of America
22px-TexasFlag-OurAmerica.png Republic of Texas

22px-Bandera_de_Iturbide.png Mexican Empire


US flag 48 stars President Henry Clay
US flag 48 stars Gen. Ennis T. Young
US flag 48 stars Gen. Franklin Pierce
US flag 48 stars Gen. William J. Worth
22px-TexasFlag-OurAmerica.png President Samuel Houston

Emperor Augustin I
PM Antonio Lopez de Santa Anna
Gen. Juan Lupe Valdez
Gen. Carlos Hauffe

The American-Mexican War, in the United States known simply as the Mexican War and in Mexico as the Second Texan War, was a conflict between 1839 and 1845 involving the United States of America, Republic of Texas and the Empire of Mexico. The war was fought primarily in the future state of Texas and the states of Arkansas and Louisiana, although some conflict did emerge in what would one day become California as well as in current territories of Mexico.

The war resulted in an American victory following Taylor's Gambit, a brave landing at Veracruz that caught the Mexicans by surprise and with their capital at Ciudad Mexico unprotected. The American government demanded enormous concessions from the Mexican government resulting in the cessation of vast amounts of territory, including the modern states of Texas, New Mexico, California, Peninsula, Colorado, Nevada, Deseret, and parts of Sequoyah and Kansas. The war, to some historians, represents the moment that the United States cemented itself as the major New World power, as opposed to allowing then-mighty Mexico from achieving that role.

Background to Conflict

Hapsburg Mexico

The Mexican Empire, established in July 21, 1821 was a monarchy without a monarch. Despite achieving its independence after 11 years of war between Mexican patriots against loyalists to the Spanish crown under José I de Bonaparte, it was divided between the conservative factions seeking a legitimate monarch to the throne, and the liberals looking to establish a American-styled Federal Republic. The original plan was to have Mexico be ruled by the Bourbon Pretender to the throne of Spain, Ferdinand VII de Borbón, or alternatively, any member from the Bourbon household. In the meantime, Mexico would be placed under a regency council under Agustín de Itrubide, a former Loyalist, who switched sides at an opportune moment and helped secure Mexican Independence. Because of shifting Napoleonic policies, and because there was little support anywhere in France or the remaining independent European states for placing a Bourbon on another throne, it left Mexico in a precarious position.

The Mexican congress, with its increasingly liberal policies, including indirect representation to reduce the influence of the landed elite, the assignment of sovereignty to itself rather than to a monarch, and the consideration of lowering the army’s pay and reducing its size, quickly led to political instability. Iturbide would respond by taking the crown for himself, and officially becoming Emperor on May 19, 1822, after confirmation by both the people (who agreed to this via questionnaire) and by a reluctant, pro-Republican Congress (most historical sources would start his rule as Emperor to September 19, 1821, the day he was confirmed Regent of Mexico). His legitimacy to become Emperor was strengthened by his earlier marriage to his second wife, Clementina de Hapsburg in 1822. Agustín’s first wife had been Ana Maria de Huarte, who passed away in 1815 by an assassin’s bullet meant for Agustín. But because of recognition by many of the European nations as well as the United States, meant that economic ties were formed initially by the Great Powers, which allowed Agustín I to maintain his support for the military. Agustín’s policies during the 1820’s were a pseudo-dictatorship. Mexico was de jure a Constitutional Monarchy, but in practice, Agustin, with some influence by his wife, was able to appoint supporters and restricted the votes to the landed elites and his various supporters in the military. (Part of the reason that, in the election of 1824, Vicente Guerrero, one Agustín’s trusted allies in the War of Independence, was able to become Mexico’s first Prime Minister.

Mexican Election of 1828

The Election of 1828 took place after the announcement of the resignation of the Guerrero government. Liberal candidate Manuel Pedraza, Conservative Candidate and then-Vice President Anastasio Bustamante, and newly established Nationalist Party candidate Antonio López de Santa Anna, were among those nominated to succeed Vicente Guerrero.

Santa Anna, who was at the time, the Governor of the Yucatán Province, was an ambitious man who sought to increase his power. However due to lack of funds and support, his personal projects to conquer Cuba from the Americans, as well as the reconquest of the breakaway states of Central America did not materialize. Yet, his popularity amongst the populace allowed him to successfully win the election, aided in no small part by divisions between liberal and conservative pro-Republicans, allowing him to win with a plurality, not a full majority.

The Nationalist Era

Santa Anna’s rule continued some of the dictatorial policies Agustín I started, and lessened during the later years of the Guerrero government. Santa Anna’s role in the Government saw the repression of press freedoms, increased support for Roman Catholicism, already serving as the Empire’s state religion, and also began to centralize the country, helped by the marginalization of the Emperor in Mexican Politics, despite little change to the position of the Austrian-born Mexican nobles.

These measures were also opposed by many governors who disapproved of Santa Anna’s dictatorial policies. A revolt in Zacatecas, led by its governor, Francisco García Salinas, was quashed in 1830. This would be followed by many other revolts and rebellions, with various states attempting to secede from Mexico, including the Republic of the Rio Grande (the intendencies of Coahuila, Nuevo León, and Tamaulipas, the latter containing its first two capitals, Laredo, and later Guerrero) the Republic of Yucatán (the intendency of Merida de Yucatán) and the Republic of Texas. The former two attempted secession banking on the success the Texians achieved the First Texan War (1833-1834)

The secessionist attempt at the Rio Grande, which took place after the First Texan War was concluded, fell apart the same year it was founded, in 1836, due in part to defections from the rebel forces, despite the unofficial attempt by Texas to support them. The Republic of Yucatán, however, since its declared independence in 1838, managed to remain in rebellion throughout the Centralist Period, and even during the American-Mexican War itself. It was only due to the direct military action of the Mexicans, and indirectly, both Mayan nationalist movements and no recognition from other powers, including the United States, which caused the downfall of the Yucatecan state in 1848.

First Texan War

It was the Republic of Texas however, that saw the most success in the Centralist Crisis. Unlike the other rebel states, Texas was inhabited by many Americans, who moved to Texas since 1822. By 1831, there were roughly 30,000 Texian Anglos to roughly 8,000 Tejanos (Spanish-speaking Texians). Santa Anna tried to control the influx of immigration by rescinding the property tax law, a prohibition of immigration into Texas (though not to the rest of the country) and the prohibition of slavery led to increased agitation in the state. It wasn’t until Santa Anna began centralizing the country that Texan leaders finally revolted against the government.

The Mexican Army, led by Austro-Mexican general Luis de Welden, did win initial victories over the Texans, capturing Goliad, Gonzales and securing San Antonio de Bexar after a siege (completed December 11). However, a stunning Texan victory at San Patricio on March 2, 1835, as well as a guerrilla war involving volunteers from all across the United States started to sap the morale of the Imperial Army, and leading to Santa Anna’s infamous decision to treat all rebels as pirates and to kill them all. This policy, carried out at the Battle of Refugio on March 15 led to the Refugio massacre, and the murder of 400 Texians and volunteers. Yet victory at San Jacinto on March 22, and again, this time decisively at San Antonio de Bexar (April 2) led to the capture of Welden, and forced Mexico into the Treaty of Santiago de la Monclova, which was to affirm Texas’ independence. But Santa Anna refused to sign the treaty, and the Mexican Parliament refused to ratify it, still believing that Texas could be won. It was only due to the combined threats of both the United States and France that forced the Mexicans to back down. Both nations, followed shortly by England, recognized the independent state.

Annexation Crisis and a Call to Arms

In the period between the end of the First Texan War and the Second, Texas, under Texian President Samuel Houston sought to incorporate the new Republic into the United States, a move which was supported by sitting President Henry Clay. On February 28, 1839, the U.S. Senate barely passed the annexation Treaty, otherwise known as the Treaty of Velasco, 35-16. This move would be later passed by the Texan Senate on June 8. Still unsolved was a considerable territorial dispute between the Mexicans and Texians over where the border would be drawn - the Mexicans claimed territory all the way to the Nueces, while Texas claimed land all the way to the Rio Grande as well as a significant portion of Nuevo Mexico. The Treaty of Velasco explicitly spelled out an American claim to all lands claimed by Texas, likely stoking Mexican resentments that would not have existed had the annexation merely laid claim to the Republic of Texas as recognized by the crown.</p>

When news of this plan of annexing Texas reached Mexico City, it had shocked and angered many of the populace, chief among them, Emperor Agustín I and Santa Anna. The Mexican Ambassador to the United States, Valentin Canalizo sent a letter requesting that the United States cease its plans to annex Texas, yet the plan to do so continued. For Santa Anna, it provided him with a grand opportunity, in addition to reclaiming Texas, Santa Anna could try and claim territory from the United States when they intervene. Santa Anna felt confident that his military, which had been trained with more Napoleonic-styled European military tactics, efficient weapons copied from the French and Austrian and Austrian-trained Mexican generals, would be able to trump the inferior “ragtag bunch of misfits.”

Further outrage spread in Mexico when Santa Anna claimed that a Mexican garrison at Castilla Real, within the neutral zone, was attacked on July 28 by American soldiers. In reality, American soldiers had not yet entered Texas and the "ambush and massacre," as Santa Anna referred to it in a fiery address to the Mexican Congress, was really a misunderstanding between a Mexican garrison and a Texian patrol that had resulted in an exchange of gunfire leaving one Mexican soldier, Juan Guzman, dead and two Texians wounded and later captured. Santa Anna brought the Texians to be tried as criminals in Mexico City and claimed that it was an act of war. They were hung on August 10 and upon receiving word of this event, both Texas and the United States promptly withdrew their ambassadors from Mexico City in horror.

Viewing this move as a sign of Anglo retreat and weakness, an emboldened Santa Anna issued an ultimatum on August 31, Texas must rescind its planned annexation, and make the Americans withdraw from their territory within the next 14 days, or they will respond with war. Mexico began to mobilize its forces along the Rio Grande River border with Texas, with Texas doing the same. Upon the deadline of the ultimatum on September 14, 1839, the Empire of Mexico declared war on the Republic of Texas.

The Mexican Invasion: 1839-1842

Valdez Crosses the Rio Grande

On September 14, 1839, Prime Minister Santa Anna ordered Juan Lupe Valdez and his 65,000 strong army across the Rio Grande with a singular goal - to reclaim Texas. By this point, the annexation crisis was over and the raid against Castilla Real a distant memory. Santa Anna's greater visions of the invasion of Texas included an eventual attack against New Orleans, which would be buttressed by his plans for an expanded Navy.

Initially, the Mexican Army had a serious advantage over both the fledgling Texan Republic and the United States Army that was expected to arrive shortly. The Mexican Army was professional, larger, better trained, and had more modern weapons. On top of that, the small minority of Austrian expatriates who had littered the upper echelons of Mexican culture had brought with them European military tactics and, with some senior officers, experience from the wars with Napoleon twenty-five years prior. The most prominent Austrian-born Mexican general was Carlos "El Rojo" Hauffe, who had moved to Mexico in 1820 and who had served at Prislitz and Buda as a young artillery officer. Hauffe was assigned the 35,000 strong Army of Santa Fe, which would cross the Rio Grande farther upriver with the intention of securing the Santa Fe Trail and prevent American settlers living in California or New Mexico to rise up in rebellion like Texas had.

Valdez's army arrived in San Antonio on September 23rd and promptly defeated the small Texan Army waiting for them. The Texan Army retreated back across the Nueces shortly thereafter towards Sutton, hoping to avoid a direct engagement with the Mexicans on open ground.

Hauffe secured Santa Fe in early October as the United States Army, with a declaration of war from Congress in hand, crossed the Mississippi and entered the Republic of Texas' territory. A planned landing of 12,000 troops at Galveston was eventually abandoned due to a storm in the Gulf of Mexico and the United States 2nd Army, commanded by Ennis T. Young, arrived in Houston on October 3rd before preparing to move against Sutton.

On October 5th, Valdez launched his assault against Sutton, setting the city ablaze and capturing the small town within the matter of hours with minimal casualties on both sides. With the fall of the capital, most members of the Texian Congress fled to Houston and Galveston further east, with the Mexican Army hot on their heels.

As Hauffe advanced northwest towards the U.S. state of Arkansas & the Indian Territory, Valdez would meet a combined, but significantly smaller American-Texan Army numbered at around 15,000 led by Brigadier General Franklin Pierce near the outskirts of Houston on October 23. Despite the tenacity of the Americans, the will of the Mexican Army & their better training was able to, as Santa Anna predicted, defeat the Anglos in battle, forcing the members of the U.S. Army, as well as the Texan congress to flee further to Louisiana.

Battle of Baton Rouge

The Mexican Army under Valdez continued pressing into Louisiana, crossing the border on November 10, but Valdez, knowing how his overland supply lines were susceptible to attack by Texan guerrillas, held position at Vermillionville, some 150 miles west of New Orleans to fortify supply lines and regroup. William J. Worth, who replaced General Pierce after his disastrous defeat at Houston, led a new, 48,000-strong Army of the Mississippi across the Mississippi to defeat the Mexican Army. The Army of the Mississippi consisted of the survivors of the Battle of Houston, along with reinforcements shored up to the front lines from southern ports such as Mobile, Alabama & New Orleans.

By the time the Mexicans restarted their advance on November 25, the Americans now had sufficient forces available to combat the Mexicans between Baton Rouge and New Orleans. It was the following day, November 26 that advance Mexican troops penetrated to within a day’s march of the city, where they awaited reinforcements. Worth took this time to attack to erect fortified ramparts and makeshift trenches, surrounded by impassible swamps and separated by the Mississippi River. Fresh Mexican troops would arrive, and Valdez, confident that they could breach the defenses, began ordering a direct attack at the dawn of November 27, taking advantage of an early morning fog.

What resulted was a bloody battle, where casualties mounted on the Mexicans trying to get through across the part of the River. Despite making two successful beachheads at opposite ends of the city, and sufficient men and firepower to try and outflank the defenders, the U.S. Army forces were able to prevent the Mexicans from surrounding the city and eventually forced them back across the river. Valdez was forced to retreat back to Vermillionville after nine days of near-continuous fighting.

It was a great victory that helped to raise the morale of the beleaguered Americans. The informal annexation of Texas on December 14, 1839 would also help in this manner as well. However, even with this victory, it would still take much of the following year to force the Mexicans out of Louisiana.

The Ozark Campaign

Battle of Santa Maria

Battle of Covenant

The Rio Grande Campaign and Invasion of California: 1842-1844

Love's Texan Campaign

Siege of Matamoros

The Free State of California and Preston's Landing

Battle of Santa Barbara

Santa Rosa Campaign and Battle of Ciudad Roderigo

American Success at Last: Monterrey and Ciudad Chihuahua

The Final Campaigns: 1844-1845

New Leadership at Home and in the Field

Victory at Santa Fe

Battle of the Brazos

Taylor's Gambit and Battle of Veracruz

Battles of Cerro Gordo and Puebla

The Battle of Rio Real and Capture of Mexico City

Aftermath and Legacy

Treaty of Veracruz

Later Tensions and Cessations

America as a Military State

Post-War Mexico