By Allen C. Guelzo,PhD, Gettysburg College
As Americans swarmed into the territories of the Louisiana Purchase, they triggered a major conflict with Mexico over American immigration into its northern province: Texas. This heated conflict spawned a Mexican uprising that resulted in the famed siege of the Alamo in 1836.

As late as 1820, Spain still clung tenaciously to large parts of the new world empire it had won under the conquistadors of the 1500s, but Spain’s political strength had been ebbing for 200 years. By 1800, it had proven more and more difficult for the Spaniards to control an American dominion that still stretched from the southern cone of South America up to the Missouri and Mississippi rivers. One by one, pieces of that dominion in South America had thrown off Spanish rule and established republics based on the liberties and slogans of the American Revolution of 1776.
Then, in 1820, the Spanish king was challenged by an uprising among his own officers that demanded reform and a republic. While Spanish attention was preoccupied with Spain’s own revolutionary problems, the Spanish province of Mexico took its future into its own hands and established a revolutionary monarchy under Agustin Iturbide in 1821. Iturbide’s monarchy proved only marginally more popular and marginally more successful than Spain’s. In 1823, Iturbide was overthrown, and the following year, a republic was established.

This is a transcript from the video series The History of the United States, 2nd Edition. Watch it now, Wondrium.
The Mexican Republic had a rocky history, especially since the individual Mexican states had notions of independence and autonomy that were not unlike some of those held by their American neighbors. At length, in 1833, an ambitious general, Antonio Lopez de Santa Anna, solved the republic’s problems by overthrowing it and setting up a personal dictatorship of the Napoleonic model.
Colonizing Coahuila
In the meanwhile, the Mexican states dealt with their internal problems by their own lights. For the state of Coahuila, which included the province of Texas, the principal problem was the sparsity of its population. From the 1820s onward, Coahuila proposed to cure that barrenness by franchising out large vacant stretches of eastern Texas prairie to land-hungry Americans. Guided by impresarios and land brokers like Moses and Stephen Austin—who acted as middlemen between Coahuila and potential American settlers—large colonies of Americans migrated to Texas, some 20,000 of them by the end of the decade and 30,000 by 1835. These immigrants found, under the Mexican flag in Texas, a land perfectly formed for livestock and farming, especially cotton, and cotton meant slaves.

By 1830, the Anglo-Americans in Texas already had 1,000 African American slaves working in the rich new cotton fields of eastern Texas. What had, at first, seemed like the ideal solution to their population problem and the emptiness of their land soon turned sour for the Mexicans. Not only did the American colonists in Texas blithely disregard agreements that bound the colonists to convert to Roman Catholicism and adopt Spanish as the civil language, but their numbers eventually dwarfed the tiny Mexican population of Texas. Anxious that the Americans would soon attempt to set up an independent Texan government, Santa Anna stripped the Mexican states of their internal autonomy and attempted to seal off the Texas border with Louisiana to control immigration from the United States.
However, the Mexican troops, under the clumsy command of Santa Anna’s brother-in-law, instead provoked an uprising in Texas. In December of 1835, the enraged Texans drove Santa Anna’s men back across the Rio Grande River into Coahuila. The resulting Texan War of Independence was short but spectacular. Many of the Mexican grandees of Texas had no more love for Santa Anna’s dictatorship than the American colonists did. The Texanos and their Anglo neighbors declared Texas an independent republic in March of 1836.
Learn more about the 11 million Africans who were torn from their homes to be slaves
“Remember the Alamo!”
At first, the odds of the republic’s survival were not good. Santa Anna gathered an army of 4,000 men and staged a midwinter march into Texas that threw the Texans into a panic. The small Anglo-Texano garrison in San Antonio barricaded itself into a crumbling Catholic mission known as the Alamo and held up Santa Anna’s advance for 13 days until a predawn Mexican attack overwhelmed the Alamo’s 183 defenders.

The Alamo was not a particularly significant engagement from a military point of view. The Alamo garrison had originally been instructed to blow the place up and retreat. Santa Anna did waste the lives of a few hundred of his men in the effort to capture the Alamo, but that was not enough to cripple his invasion effort. What turned the Alamo from being a military annoyance into a catastrophic misjudgment was Santa Anna’s temperamental decision to put every survivor of the Alamo garrison to death.

Across eastern Texas, the American colonists were both terrified and outraged, and “Remember the Alamo” became an electrifying war cry for them. A small, ragtag Texan army under an old protégé of Andrew Jackson named Sam Houston fell back before Santa Anna’s advance, lulling the Mexicans into a sense of assured and easy conquest. Then, on April 21, 1836, Houston and the Texan army turned and struck the Mexicans at San Jacinto, routing the Mexican army and capturing Santa Anna himself. As a condition of his release, Santa Anna signed an agreement recognizing Texan independence, an agreement that, of course, was immediately repudiated when Santa Anna reached Mexico City again.
The aim of the Texans was not to remain independent, however, but to join the United States as a new state as soon as possible.
Learn more about how the United States gained all of what is now the American Southwest
An Unwilling, Independent Republic

But the trouble began all over again. Martin Van Buren—Andrew Jackson’s anointed successor—was elected president in 1836. As a Democrat, Van Buren owed a great deal to the Democratic constituencies of the southern states. Van Buren was also a New Yorker who was less than eager to promote the expansion of slavery and involve the United States in a dispute over a province that was still technically the property of Mexico.
The panic of 1837 only complicated things, because Van Buren was not eager to assume responsibility for the debts the Texans had run up in financing their revolution. Then, in 1840, the presidential election of that year brought a Whig to the presidency for the first time, in the person of William Henry Harrison. The Whigs preferred to pour the nation’s resources into developing the internal American economy rather than picking up the bills for expansionist adventurers elsewhere. Consequently, Texas remained an unwilling but independent republic.

But, William Henry Harrison died only one month after his inauguration as president, and the Whig Party suddenly found itself saddled with Harrison’s vice president, John Tyler, who was soon at odds with Henry Clay and Daniel Webster, the real chiefs of the Whig Party.
Every bill that Clay and the Whig Congress wrote for the pet projects of the Whigs—bills for internal improvements, protectionist tariffs, a new Bank of the United States—were all vetoed by John Tyler. Eventually, all the Whigs in the cabinet resigned.
Shunned by the Whigs, Tyler tried to assemble his own independent political power base, and as a Virginian and a slaveholder, Tyler was not shy of bidding for southern support. As bait to his fellow southerners, Tyler and his new secretary of state, Abel Upsher, negotiated an annexation treaty for Texas. Unfortunately, they tried to turn Texas annexation into a campaign issue that John Tyler should have been able to ride back into the White House in 1844.
Learn more about the signing of the Treaty of Ghent
Common Questions About the Alamo
“Remember the Alamo” is a battle cry meant to motivate bravery by commemorating one of the famous battles where a group of 900 Texans fought off the Mexican army, killing over 600 troops before succumbing to defeat.
Mexico was unhappy with the Texans for failing to integrate into Mexican culture, adopt their language, and convert to Catholicism. Additionally, Mexico had outlawed slavery, which was at odds with the fact that many Texans used slaves to farm cotton. Mexico seized the Alamo to right the many wrongs they perceived with slavery, unchecked immigration, and the financial gain Texans were enjoying at the expense of all others in the region.
The Alamo was a church mission built in the 18th century to convert Native Americans to Christianity.
The most famous men who fought at the Alamo were Davy Crockett and James Bowie.