The Alamo was originally established by Catholic missionaries in 1718. One of five that eventually dotted the San Antonio landscape, it fell under the jurisdiction of the College of Santa Cruz of Querétaro. Founded to convert the area's original inhabitants -- Native American tribes including the Apache, the Karankawa, the Tacame, and the Pamaya -- to Catholicism, it was followed by a regional military outpost, San Antonio de Béxar Presidio, and by a civilian settlement, San Fernando de Béxar. The three settlements competed for the area's water and land resources, but joined together to defend themselves from Native American attacks.

In 1793 the Spanish Crown secularized the mission, splitting all but its religious offices among the growing Béxar community of presidio soldiers, settlers, and Native Americans connected with the mission. In the 19th century, the structure served a variety of functions. A mobile squadron, the compañia volante ("flying company"), quartered there and patrolled the region. The company, from a pueblo Alamo de Parras in Coahuila, gave the mission the name of their town of origin -- and the name stuck. Later the mission served as a hospital to the region.

After Mexico independence in 1821, the Alamo became a symbol of Mexican authority on the Texas frontier. When Santa Anna assumed the Mexican presidency and subsequently overhauled the federalist administration in favor of a centralist one, tensions between his government and the Texans began to mount. When the tensions ignited in the Battle of Gonzales, sparked by Anglo colonists' refusal to cede a cannon to Mexican troops, Santa Anna sent a garrison under General Martín Perfecto de Cos to San Antonio. They seized the town and fortified the Alamo. The two-month siege ended when Anglo and Tejano revolutionaries retaliated in a five-day attack, known as the Storming of Béxar. Cos surrendered and left Texas in disgrace in December 1835.

Now in the hands of the rebels, the Alamo was the site of a particularly important election in the Tejano community. On February 1, 1836, nearly one hundred Tejano citizens of Béxar held a meeting inside the Alamo's walls to elect who among them would go on to Washington-on-the-Brazos as their representative at Texas' Independence Convention. They chose forty-one-year-old José Antonio Navarro and his uncle, Colonel José Francisco Ruiz. Both men had been prominent leaders in the community for so me time.

Anticipating the Mexicans' return, the Texas army fortified the Alamo. On February 23, 1836, Santa Anna and his Army of Operations entered Béxar and the Alamo became a fortress for the rebel fighters, a hiding place for most of the women and children of San Antonio, and a battleground. After a twelve-day seige, the compound, including its chapel, was overrun by the Mexicans and badly damaged. In the bloody aftermath, the Alamo was littered with the bodies of its defenders, and those of the  Mexican soldiers they had killed.

After the United States annexed Texas in 1845, the U.S. military occupied the Alamo, and during a brief period during the Civil War, it was held by the Confederacy. The late nineteenth century brought more newcomers to San Antonio, and the city gradually built around the aging mission. In 1883 the state of Texas bought the chapel, which had survived virtually intact from the Catholic church. In 1905 it bought the other buildings, and granted custodianship of the site to a private organization, the Daughters of the Republic of Texas, which maintains the Alamo as a San Antonio tourist attraction today.