Alamo is a historic structure in the center of San Antonio. A famous battle was fought there from February 23 to March 6, 1836, during the war for Texan independence. To prevent the success of this independence movement, General Antonio Lopez de Santa Anna, in command of the Mexican Army, approached San Antonio with his troops. Lieutenant Colonel William Barret Travis and a force of about 150 Texans, included the famous frontiersmen James Bowie and Davy Crockett, tried to defend the city against approximately 4,000 Mexican troops. The siege of Alamo lasted 13 days and all the Texans who fought died in the battle, except Susanna Dickinson, her baby, her Mexican nurse and Colonel Travis' black slave Joe. The determined defense of the Alamo gave General Sam Houston time to gather the forces he needed to save Texas and on April 22, Houston's army captured Santa Anna and forced him to sign a treaty, granting Texas its independence.