Following his brother's instructions, Leonard Calvert at first attempted to govern the country in an
absolutist way, but in January 1635, he had to summon a colonial
assembly, which became the foundation and first session of the modern
General Assembly of Maryland, the third legislature to be established in the English colonies after the
House of Burgesses in the Dominion of
Virginia and the
General Court in the Commonwealth of
Massachusetts. In 1638, the Assembly forced him to govern according to the
common law of
England, and subsequently the right to initiate legislation passed to the new
General Assembly, representing the common "freeholders" (owners of
freehold property) as subjects of the Crown. In 1638, Calvert seized a trading post at
Kent Island established by the Virginian
William Claiborne. In 1643, Governor Calvert went to England to discuss policies with his brother Lord Baltimore, the proprietor, leaving the affairs of the colony in charge of acting Governor
Giles Brent, his brother-in-law (he had married Ann Brent, daughter of Richard Brent). Calvert returned to Maryland in 1644 with a new wife and children (William, born in 1643, and a daughter, Anne, born in 1644). That same year, Claiborne returned and led an uprising of Maryland
Protestants against the Catholic Proprietor. Calvert was soon forced to flee southward to
Virginia. He returned at the head of an armed force in 1646 and reasserted
proprietarial rule. Leonard Calvert died of an illness in the summer of 1647. Before he died, he wrote a will naming
Margaret Brent (the sister of Giles and a future, historically famous planter, lawyer, and female advocate for women's rights) as the executor of his estate. Calvert also named his friend and fellow passenger aboard
The Ark and
The Dove,
Thomas Greene, as his successor to the governorship. In 1890, the State of Maryland erected an obelisk monument to Calvert and his wife at
Historic St. Mary's City which had a historical district created to commemorate the colonial origins of the colony. ==Leonard Calvert's lost grave==