At the end of the seventeenth century, Antonio de San Buenaventura y Olivares was an aging and often cantankerous priest who had spent many years as missionary in the province of Zacatecas. In 1699 Father Antonio Margil de Jesús, guardian of the College of Santa Cruz de Querétaro, chose two fellow Franciscans, Olivares and Marcos de Guereña, for work in northern Coahuila. The new priests joined Father Francisco Hidalgo at San Juan Bautista, at first located on the Río de Sabinas. Olivares was present at the founding of the second San Juan Bautista, begun on January 1, 1700, at the site of modern Guerrero, Coahuila. Another mission, San Francisco Solano-destined to loom large in the history of Texas-was founded in the same locale by Father Olivares on March 1, 1700. It apparently served Indian hunters and gatherers beyond the Rio Grande in Texas. For many years Olivares was closely associated with this mission and its more famous successor.
In 1706 Olivares was summoned to his college to serve as its guardian. He remained in Querétaro until 1709, when the viceroy ordered him to return to the gateway missions near the Rio Grande. In that same year Olivares served as chaplain to an expedition captained by Pedro de Aguirre, which advanced to the site of San Antonio and beyond it to the Colorado River. The overall result of this undertaking was to dispel the optimistic hope that the Tejas Indians would welcome the return of Spanish missions in East Texas. For Olivares the disappointing news meant a long journey to Spain, where, as an advocate for expanded missionary activities in Texas, he remained for six years. By 1716 he was back in New Spain, determined to found a mission at the site he had visited on the San Antonio River in 1709.
At San Juan Bautista, Olivares-never one to shy away from controversy-leveled charges that Capt. Diego Ramón and his sons, as well as Louis Juchereau de St. Denis, their relative by marriage, were involved in a massive contraband enterprise. When the resulting investigation failed to prove any wrongdoing on the part of the Ramóns and St. Denis, Olivares directed his wrath at Martín de Alarcón, the investigating officer and new governor of Coahuila and Texas. Alarcón's entrada, charged with founding a mission, presidio, and settlement on the San Antonio River, finally departed San Juan Bautista on April 9, 1718, but Olivares refused the company of the governor. Separately, traveling with a small escort, he reached the river on May 1. On that same day Alarcón awarded Olivares possession of San Antonio de Valero Mission. Technically, the new religious outpost represented a new site for Olivares's largely failed mission, San Francisco Solano. After Spanish personnel retreated from East Texas to San Antonio in 1719, Margil received permission from the Marqués de San Miguel de Aguayo to found a second mission at San Antonio. Despite the determined opposition of Father Olivares, San José y San Miguel de Aguayo Mission, founded for the Zacatecan Franciscans, was officially established on February 23, 1720.
On September 8, 1720, Olivares-aged, in poor health, and suffering from a broken leg-retired from Mission Valero. It is reasonable to assume that he spent his remaining days at San Juan Bautista, or perhaps in Querétaro. His most notable contribution was the founding of San Antonio de Valero, the best-known mission in Texas history (see ALAMO).