The Alamo was founded in 1718 as a Spanish mission during the original settlement of San Antonio, TX. It was secularized in 1792, fell into decay, and later was used as a hospital and a troop garrison. When Antonio Lopez de Santa Anna invaded Texas during the Texas Revolution, the Texans withdrew behind the Alamo's crumbling walls. Some 190 defenders were under siege by an army of nearly 6,000 men. Artillery fire continued for 12 days, and on the 13th day the Mexicans broke through and massacred all of the Texas men. A Mrs. Dickenson, her child, and possibly two servants were the only non -Mexicans to survive. Only four days before, a convention had declared Texas independence. This was unknown to those who died at the Alamo. They died fighting under the Mexican flag, defending the Mexican constitution of 1824, which Santa Anna had abrogated.