Early life and education
John Carroll was born to Daniel Carroll I and Eleanor (Darnall) Carroll at the large plantation which Eleanor had inherited from her family. He spent his early years at the family home, sited on thousands of acres near Marlborough Town, the county seat of Prince George's County in the Province of Maryland. (Several remnant surrounding acres are now associated with the house museum known as "Darnall's Chance", listed on the National Register of Historic Places and part of the system of the Maryland-National Capital Park and Planning Commission for northern suburban Washington, D.C.).
Other Carroll relatives were instrumental in the development of the colonial Province of Maryland and the establishment of Baltimore (1729), soon to be the third-largest city in America, and developed as a port on the Chesapeake Bay. His older brother Daniel Carroll II (1730–1796) became one of only five men to sign both the "Articles of Confederation and Perpetual Union" (1778) and the Constitution of the United States (1787). His cousin Charles Carroll (1737–1832) was also an important member of the Revolutionary Patriot cause, and was the last surviving signer of the Declaration of Independence (1776). Charles Carroll lived long enough to participate in the industrial revolution, with the ceremonies of the 1828 setting of the "first stone" for the beginning of the construction of the Baltimore and Ohio Railroad.
John Carroll was schooled at home by his mother, before being sent to a Catholic school at Bohemia Manor in Northeastern Maryland, secretly conducted by Father Thomas Poulton, a Jesuit. At the age of thirteen, he was sent to the College of St. Omer in French Flanders (northern France, bordering southern edge of modern Belgium). (This was established for the education of English Catholics after they suffered discrimination following the Protestant Reformation instituted by King Henry VIII in England). During the upheavals of the French Revolution (1789–1799), the College migrated to Bruges, and then Liège. It returned to England and was located at Stonyhurst in 1794, where it remains today.) Also attending St. Omer with him was his cousin Charles, who was to become the only Catholic signatory of the Declaration of Independence, and the first United States Senator (1789) from Maryland.