Laurence Julius FitzSimon, Catholic bishop and historian, was born in San Antonio, Texas, on January 31, 1895, son of John Thomas and Theodora (Okelmann) FitzSimon. The family moved the following year to Castroville, where John FitzSimon practiced medicine until his death in 1924. At the age of twelve, Laurence was sent to St. Anthony's College in San Antonio. In 1911 he was sent by the Diocese of San Antonio to Rome to complete his studies for the priesthood. Ill health forced him to return to Texas in 1916. After recuperating for a few months, he joined the United States Navy and was assigned to the minesweeper Heron during World War I as a pharmacist's mate.
FitzSimon resumed his theological studies in 1919 at St. Meinrad's Seminary, Indiana, and was ordained on May 17, 1921. After teaching for four years at St. John's Seminary, San Antonio, and then serving as pastor at Runge, Karnes City, and Kenedy for seven years, he was transferred to Seguin in 1932. While there he directed the activities celebrating the founding of Seguin and wrote a history of Seguin and a pageant on the city's founding.
In 1941, when Bishop Robert E. Lucey of Amarillo was made archbishop of San Antonio, he appointed Father FitzSimon chancellor of the archdiocese. It was a short assignment, however, for on August 5, 1941, the chancellor was named bishop of the Catholic Diocese of Amarillo. He was consecrated on October 22 and installed on November 4. During his administration the number of churches, priests, schools, and institutions in the diocese more than doubled.
FitzSimon was a scholar and historian. His Texana collection ranked among the best private historical libraries. During his custodianship of the Catholic Archives of Texas, he made frequent trips to France and Rome to gather materials on bishops and priests who had labored in Texas during the colonial period. For his research on pioneer French priests of Texas, he was awarded the title of Chanoine d'Honneur de la Primatiale in 1951 by the cardinal bishop of Lyons, the first American to be so honored.
FitzSimon suffered a stroke in May 1954 and never fully recovered, though he continued the work of his diocese and historical collecting. He died on July 2, 1958, at St. Anthony's Hospital in Amarillo and was buried in Llano Cemetery. In 1976 the bishop's personal library was donated to the Amarillo Public Library as the Bush-FitzSimon Collection. In 1989 the Texas Catholic Historical Society established the Laurence J. FitzSimon Award to honor Catholic archivists in Texas.