Winthrop accompanied the ill-fated expedition of the Duke of Buckingham for the relief of the Protestants of La Rochelle, and then he travelled in Italy and the Levant, returning to England in 1629. In 1631, he followed his father to Massachusetts Bay Colony and was one of the assistants of the Colony in 1635, 1640, and 1641 and from 1644 to 1649. He was the chief founder of Agawam in 1633, then went to England in 1634. He returned in 1635 as governor of lands that had been granted to Lord Say and Sele and Lord Brooke, and he sent out a party to build a fort named Saybrook in their honor, located at the mouth of the Connecticut River. He then lived for a time in Massachusetts, where he devoted himself to the study of science and attempted to interest the settlers in the development of the colony's mineral resources. He was again in England in 1641–43, then returned to establish iron works at Lynn and Braintree, Massachusetts. In 1645, he obtained title to lands in southeastern Connecticut and founded New London in 1646, where he settled in 1650. He built a grist mill in the town and was granted a monopoly on the trade for as long as he or his heirs maintained it. This was one of the first monopolies granted in New England. One of Winthrop's Indian servants was Robin Cassacinamon, who became an influential Pequot leader through Winthrop's patronage.
Governor of the Connecticut Colony
Winthrop became one of the magistrates of the Connecticut Colony in 1651, was governor of the colony in 1657–58, and again became governor in 1659, being annually re-elected until his death. During his tenure as Governor of Connecticut, he oversaw the acceptance of Quakers who were banned from Massachusetts. In 1662, he obtained the charter in England which united the colonies of Connecticut and New Haven. He was also one of the commissioners of the United Colonies of New England in 1675. While in England, he was elected as a Fellow of the newly organized Royal Society, and he contributed two papers to their Philosophical Transactions: "Some Natural Curiosities from New England" and "Description, Culture and Use of Maize". His correspondence with the Royal Society was published in series I, vol. xvi of the Massachusetts Historical Society's Proceedings.
Personal life
Winthrop married his cousin Mary Fones, the daughter of Thomas Fones II and Anne on February 8, 1630/1. She and their infant daughter died in Agawam in 1634. Winthrop's second wife was Elizabeth Reade, the daughter of Col. Edmund Reade and Elizabeth. They had nine children, including:
Elizabeth Winthrop, who married Rev. Antipas Newman and Dr. Zerubbabel Endecott, son of Gov. John Endecott
Fitz-John Winthrop, who served as major-general in the army, an agent in London for Connecticut, and governor of Connecticut from 1696 until his death in 1707
