Leonard Calvert was the first proprietary governor of the Province of Maryland. He was the second son of The 1st Baron Baltimore (1579–1632), the first proprietor of Maryland. His younger brother Cecil (1605–1675), who inherited the colony and the title upon the death of their father George, April 15, 1632, appointed Leonard as governor of the Colony in his absence.

The Province of Maryland was an English and later British colony in North America from 1634 until 1776, when the province was one of the Thirteen Colonies that joined in supporting the American Revolution against Great Britain. In 1781, Maryland was the 13th signatory to the Articles of Confederation. The province's first settlement and capital was in St. Mary's City, located at the southern end of St. Mary's County, a peninsula in the Chesapeake Bay bordered by four tidal rivers.