The Missionary Oblates of Mary Immaculate, founded in France in 1816 by Blessed Eugene de Mazenod, quickly became a mission-sending society of priests and brothers. The Texas mission began in 1849 with five Oblates; by 1883, forty-one had served. They established schools in Galveston (1855) and Brownsville (1865), but their principal ministry was circuit-riding, by which they served briefly in East Texas (1853–55) and from 1849 onwards in South Texas.
In 1849 Bishop Jean Marie Odin entrusted to the Oblates' care the area that now comprises the eight southernmost counties of Texas. They established headquarters in the new town of Brownsville. As more Oblates arrived, a second headquarters was founded at Roma (1854), the most distant place reached by commercial riverboats, and a halfway stopover at La Lomita Ranch (1861). Later the town of Mission was built on part of this ranchland and named after the Oblate chapel there. From these centers the padres of the "Cavalry of Christ," in black soutane with the Oblate cross hung from the neck, fanned out on horseback to serve hundreds of scattered ranches. Their six-week circuits took them 100 miles or more into the interior. The memory of Father Jean Baptiste Bretault is still revered by coastal ranch families between Brownsville and Kingsville. Another famous member of this group was Father Pierre Yves Keralum, missionary circuit-rider and architect. Oblates were involved in the tumultuous events of early Valley history: border lawlessness, civil wars in the United States and Mexico, yellow fever, and hurricanes. Seven died between 1853 and 1862, leading Mazenod to exclaim, "Cruel Texas mission!" Two were forcibly exiled from Ciudad Victoria in 1860, and three were imprisoned in Matamoros in 1866, during the era of Benito Juárez in Mexico.
As Texas became more widely settled, the Oblates accepted ministries in San Antonio (1884) and in the West Texas counties as far west as Eagle Pass and Del Rio (1883). In 1904 San Antonio became their Texas headquarters. With the advent of the railroads and the establishment of their own school for training priests in San Antonio, it was practical for Oblates to offer services after 1904 to seventeen counties of Central Texas, then to eight counties of north central Texas and fifteen counties of the Plains and Panhandle. In 1911 and after ministry was accepted in eighteen counties between Houston, Austin, and Palestine.
When the automobile replaced the horse, Father Yves Tymen brought Mass to the scattered Valley ranches in the St. Peter Chapel Car (1913), an oversized van with living facilities for two, that could be enlarged by a tent to become a chapel. Father Charles Taylor (1896–1967) organized the first farmworkers' union in Texas on November 10, 1930, in Crystal City. The Catholic Workers Union, made up of Mexican-American laborers in Zavala and Dimmit counties, reached an agreement with local growers that recognized the right to a living wage and provided for children to be sent to school. In 1953 Father Edward Bastien (1907–1972) organized the people of Zapata, when the townsite was about to be inundated by Falcon Lake, and insisted on a fair compensation for their homes. The federal government agreed to replacement value, thus making possible the reconstruction of the town. Father Antonio Gonzales (b. 1927) led a farmworkers' march from Rio Grande City to Austin between July 4 and September 6, 1966, to demand a minimum wage. Two days after the 10,000-person rally, Congress extended the minimum wage to farmworkers for the first time.
In all, by the late 1980s Oblates from the United States and eighteen foreign countries had served ninety-three Texas counties. From their San Antonio headquarters they also had staffed missions in California, Colorado, New Mexico, Louisiana, Mexico, and Zambia. The order numbered 335 men, its peak, in 1967. In 1985 there were 248 Oblates serving in thirty-five Texas counties, Colorado, Louisiana, Mexico, and Zambia. In Texas, ranch ministry had in large part yielded to urban apostolates. Ministry to the Mexican Americans, with growing attention to undocumented immigrants, still predominated. Among the ministries were the Oblate School of Theology (1903), St. Anthony Seminary (1905), and the Lourdes-Guadalupe Pilgrimage Shrine (1941), all in San Antonio; the Virgen de San Juan del Valle Shrine in San Juan (1954); and numerous parish schools. Oblates were the Catholic chaplains to the Texas Department of Corrections. They also staffed six retreat centers, eleven hospital and nursing facilities, fifty-four parishes, and twenty-one other ministries, including the bishopric of San Angelo.