José María Esparza, better known as Gregorio Esparza, defender of the Alamo, was born on February 25, 1802, in San Antonio de Béxar, the child of Juan Antonio and Maria Petra (Olivas) Esparza. He married Anna Salazar, who bore him a daughter and three sons, one of whom, Enrique, was an eyewitness to the siege of the Alamo. Esparza enlisted in Juan N. Seguín's company in October 1835 and participated in the taking of the squares on the north side of the city during the siege of Bexar, December 5–9, 1835. He served until the capitulation of Gen. Martín Perfecto de Cos on December 10, 1835.
On the arrival of Gen. Antonio López de Santa Anna in February 1836, Esparza and his family were advised by John William Smith to take refuge in the Alamo, since they had been friendly with the Texans who immigrated from the United States. They arrived at twilight and entered through a small window in the church of the compound. Although Col. William Barret Travis, through James Bowie's influence, was allowing local citizens to leave if they so desired, Esparza elected to stay and fight, and his family to remain with him. He tended a cannon during the siege and died in the battle of the Alamo on March 6, 1836.
Francisco Esparza, Gregorio's brother, by his own admission a member of the local Mexican "presidial" company of the Alamo until the capitulation of Cos, requested and was granted permission to enter the Alamo and search for his brother's body after the siege. In company with his two brothers, he took the body and interred it in the Campo Santo on the west side of San Pedro Creek. Thus Gregorio Esparza received a Christian burial, unlike the others slain in the battle. Gregorio's heirs were instrumental in founding San Augustine, southeast of Pleasanton in Atascosa County.