Adolphus Louis de Barth Walbach (November 1, 1764 – October 13, 1844), commonly known as Louis de Barth, was a Roman Catholic priest in Pennsylvania and Maryland. Born and raised in Alsace, he emigrated with his noble family to the United States during the French Revolution. He spent the rest of his life as a priest there, mostly at Conewago Chapel in rural Pennsylvania. After the Bishop of Philadelphia died in 1814, de Barth temporarily led the diocese as apostolic administrator until a new bishop arrived in 1820. After several years at a German-speaking Baltimore parish, he retired to Washington, D.C., in 1841 and died there three years later. Early life and priesthood De Barth was born November 1, 1764, in the town of Munster, in Alsace, France. He was the son of a French nobleman, Jean Joseph de Barth, and his wife, Marie Louisa de Rohme. He showed an inclination toward clerical life from an early age, and his parents encouraged him in that vocation. After attending a Premonstratensian college in Belgium, he enrolled in a seminary in Strasbourg and was ordained there in 1790. The French Revolution forced many noble families into exile, including de Barth's, and they moved to the United States in 1791. De Barth renounced his titles and presented himself to John Carroll, the bishop of Baltimore, for service as a secular priest. Initially, he worked at Bohemia Manor as an assistant priest; shortly thereafter, he was relocated to Port Tobacco, Maryland. After spending three years serving in Port Tobacco, de Barth was assigned to a church in Pennsylvania in 1795. The main church in the area, Conewago Chapel, was the center of the only parish in of the Pennsylvania frontier, an area that contained few Catholics. The sparsely populated area had been mostly settled by Germans, who were pleased to have a priest who was able to speak their native language. In 1798, Carroll visited de Barth at Conewago to tour that part of his diocese and to administer the sacrament of confirmation. Michael Francis Egan, an Irish Franciscan, joined him there in 1802. In 1804, de Barth was formally put in charge of Conewago Chapel, which had previously fallen under the jurisdiction of the Jesuits. At the same time, he continued making visitations to the small rural chapels in the area. In 1806, de Barth laid the cornerstone of a new church, St.