From the history of Sacred Heart via their website
: “One can hardly write about the Sacred Heart Catholic Church in Milledgeville without acknowledging the threads of the Treanor and Cline families that are woven ever so snugly within the fabric of the early Catholic community in Baldwin County. For over a hundred and fifty years these families, the ancestors of internationally acclaimed author Flannery O’Connor, have been instrumental in the development and growth of the Catholic Church in Milledgeville. Yet today, the church is privileged to have an active parishioner who is a decedent of these families.
The first Catholic resident of Milledgeville was Hugh Donnelly Treanor, Flannery O’Connor’s great-grandfather. Mr. Treanor owned and operated a gristmill located on the Oconee River just east of town. Remnants of the mill can still be seen when looking north from the bridge just east of town on the Sparta Road. It was in his room in the Newell Hotel, across the street from the Presbyterian Church where the Magnolia State Bank now stands, that the first Catholic Mass on record was celebrated in April 1845 by Reverend J.J. O’Connell. Documentation also shows that the O’Brien family was in attendance at the Mass.“
Milledgeville Historic District, National Register of Historic Places