​There were three major types of Spanish settlements. Missions were religious settlements. Each mission housed a small number of priests and others who worked to teach local Native Americans about Christianity and the Spanish way of life. The Native Americans also grew crops to feed themselves and the priests. To protect the missions from attacks, the Spanish built presidios, or forts. The soldiers based at a presidio could ride out to defend the priests at any nearby missions. Finally, the Spanish also created towns, sometimes called pueblos, near some missions. In these towns, Spanish citizens would live, grow crops, and raise cattle.

Missions helped create a Spanish presence in a territory and increased the Spanish occupation of the borderlands. Their main goals were to convert Native Americans to Catholicism and to teach them about the Spanish way of life.​

The political situation in the Southwest changed when Mexicans moved to overthrow Spanish rule in the early 1800s. In September 1810 Father Miguel Hidalgo y Costilla, a Mexican priest, led a rebellion of about 80,000 poor Indians and mestizos, or people of Indian and Spanish ancestry. They hoped that if Mexico became independent from the Spanish monarchy, their lives would improve.​

​In 1821 Mexico became independent. In 1824 it adopted a republican constitution that declared rights for all Mexicans.

The new Mexican government contracted with empresarios, or agents, to bring settlers to Texas. They paid the agents in land. In 1821 one young agent, Stephen F. Austin, started a Texas colony on the lower Colorado River. The first 300 families became known as the Old Three Hundred. Austin’s successful colony attracted other agents, and American settlers flocked to the region.

​These Anglo-American settlers, most of them Protestant, became known as Texians. The Mexican residents of Texas, the Tejanos, were Catholic. The two groups generally lived in separate communities. Over time, Texas developed a culture that was distinct from the rest of Mexico and from the United States.

​In exchange for cheap land, settlers had to obey Mexican laws. But some settlers often explicitly ignored these laws. For example, despite restrictions on slavery, many brought slaves. Concerned that it was losing control of the growing American population, Mexico responded. In 1830 it banned further settlement by Americans. Angry about the new law, many Texans, as they came to be known, began to think of gaining independence from Mexico.

By 1834 Mexico came under the rule of General Antonio López de Santa Anna. He soon suspended Mexico’s republican constitution and gave himself more power. To the already unhappy Texans, this was too much. They felt the time had come to fight for independence.​

In October 1835 the Mexican army tried to remove a cannon from the town of Gonzales, Texas. Rebels stood next to the cannon with a flag reading “Come and take it.” After a short battle, the rebels drove the Mexican force away, keeping the cannon. Within a few months, the Texas rebels formed an army and captured the key settlements of Goliad and San Antonio. The Texas Revolution, also known as the Texas War for Independence, had begun.​

The Texans’ actions angered Santa Anna. He began assembling a force of thousands to stop the rebellion. A hastily created army of Texas volunteers had been clashing with Mexican troops for months. Near San Antonio, the Texans occupied and fortified the Alamo, a former mission that became an important battle site in the Texas Revolution. Volunteers from the United States, including frontiersman Davy Crockett, joined Texans such as Colonel Jim Bowie in the Alamo’s defense.​

​The rebels, numbering about 200, hoped for reinforcement from other parts of Texas. For almost two weeks, from February 23 to March 6, 1836, the Texans held out. Colonel William Travis managed to get a message to other Texans through enemy lines: “I call on you in the name of Liberty, of patriotism, and everything dear to the American character, to come to our aid with all dispatch [speed] . . . VICTORY OR DEATH.”