What did john Carroll do as an important service?

John Carroll was a significant figure in American history, primarily known for his role as the first Catholic bishop in the United States. He founded the Catholic University of America and established the Archdiocese of Baltimore, which served as the center of the Catholic Church in the U.S. Carroll was instrumental in promoting religious freedom and education, championing the rights of Catholics in a predominantly Protestant nation. His leadership helped lay the foundation for the growth of the Catholic Church in America.