How many days did the Siege of the Alamo last?

The Siege of the Alamo (February 23 – March 6, 1836) describes the first thirteen days of the Battle of the Alamo. On February 23, Mexican troops under General Antonio Lopez de Santa Anna entered San Antonio de Bexar, Texas and surrounded the Alamo Mission. The Alamo was defended by a small force of Texans and Tejanos, led by William Barrett Travis and James Bowie, and included Davy Crockett. Before beginning his assault on the Alamo, Santa Anna offered them one last chance to surrender. Travis replied by opening fire on the Mexican forces and, in doing so, effectively sealed their fate. The siege ended when the Mexican Army launched an early-morning assault on March 6. Almost all of the defenders were killed, although several civilians survived.

Several months previously, Texians had driven all Mexican troops out of Mexican Texas. About 100 Texians were then garrisoned at the Alamo. The Texian force grew slightly with the arrival of reinforcements led by eventual Alamo co-commanders James Bowie and William B. Travis. On February 23, approximately 1,500 Mexicans marched into San Antonio de Béxar as the first step in a campaign to retake Texas. For the next 10 days, the two armies engaged in several skirmishes with minimal casualties. Aware that his garrison could not withstand an attack by such a large force, Travis wrote multiple letters pleading for more men and supplies, but the Texians were reinforced by fewer than 100 men.