Margaret (Mother Mary Camillus) Lucas, who established the Sisters of Mercy in Texas, was the daughter of George and Margaret (Field) Lucas of Youghal, County Cork, Ireland. As a teenager she led two siblings to America in the 1860s, including Mary Ann Lucas, leader of the Refugio Sisters of Mercy. Margaret joined the Mercy congregation in St. Louis, where she was received as Mary Camillus in 1867. In answer to the 1869 invitation of Jean Marie Odin, archbishop of New Orleans and pioneer bishop in Texas, the Mercy Sisters sent a foundation to New Orleans. Odin welcomed the sisters, including Mary Camillus, who professed her religious vows under his jurisdiction the following August.
Mary Camillus and her sister were among the three novices who moved with Mother Catherine Grant to St. Patrick's parish on October 17, 1871. Two untimely deaths in 1872-that of Father John Flanagan, who had established St. Patrick's Convent and School, and that of Superior Catherine Grant-closed this foundation. Having inherited the role of leader, Mother Camillus sought reinforcements and another mission from Odin's successor in New Orleans, Archbishop N. J. Perche. Perche's appeal in 1874 to newly consecrated Bishop Anthony D. Pellicer of San Antonio resulted in the latter's invitation to Camillus to bring the sisters to Indianola. She and a companion reached the town to survey facilities on January 6, 1875. Influenced by the pastor, Rev. Joseph Ferra, and the need for teachers at the school, Mother Camillus wired her sisters to take the next Morgan Lines steamer to Indianola.
St. Mary's Institute, the first Mercy school in Texas, opened for the spring semester of 1875. It showed such healthy growth when Bishop Pellicer visited in April to witness a recitation by the pupils and a reception of Mercy novices that he invited Mother Camillus to staff schools being constructed in Refugio and San Patricio. After gathering more teachers that August, she returned just before the September hurricane that demolished Indianola in 1875 and took hundreds of lives. After aiding stricken families, the sisters found hospitality with the gracious Sisters of the Incarnate Word and Blessed Sacrament in Victoria. The second Mercy convent in Texas opened in Refugio on October 7, 1875; many of the pupils, like their teachers, were refugees from Indianola.
When San Patricio was ready in June 1876, Mother Camillus accompanied half of the sisters to their third Texas mission. This school flourished until the severe drought of the 1880s demolished herds, ranches, and the school. In 1884 Father Ferra invited Camillus to St. Michael's School in Cuero, where both church and school expanded during her dozen years there. Camillus so enjoyed her work with the survivors of two hurricanes that it was difficult for her to move to Smithville in 1896 at the direction of Bishop John A. Forest. Mother Mary Camillus Lucas died on September 18, 1910, surrounded by her sisters in Smithville, Texas.