He featured in disputes between the colonists of Virginia and the later settling of Maryland, partly because of his earlier trading post on Kent Island in the mid-way of the Chesapeake Bay, which provoked the first naval military battles in North American waters.

He was one of the signers, along with Virginia Governor John Pott, Samuel Matthews, and Roger Smyth, of a letter to the King's Privy Council, dated 30 November 1629, complaining that Lord Baltimore refused to take the Oath of Allegiance and Supremacy to the Church of England.

[4] Claiborne was born in Crayford parish in the county of Kent in England to Sarah Smith James, the widowed daughter of a London brewer, and was baptised on August 10, 1600.

His father, Thomas Clayborn, was an alderman and lord mayor from King's Lynn, Norfolk, who made his living as a small-scale businessman involved in a variety of industries, including the salt and fish trades.

[7] The family's business was not profitable enough to make it rich, and so Claiborne's older brother was apprenticed in London, becoming a merchant involved in hosiery and, eventually, the tobacco trade.

Meanwhile, the native Powhatan people had been disturbed by the influx of immigrants, particularly new villages established on traditional farming lands, the subsequent need to purchase food from the settlers, and the enforced placement of Indian youth in "colleges.

Claiborne wanted to establish a trading post on Kent Island in the mid-way of the Chesapeake Bay, which he planned to make the center of his mercantile operations along the Atlantic Coast.

[6] Claiborne found both financial and political support for the Kent Island venture from London merchants Maurice Thomson, William Cloberry, John de la Barre, and Simon Turgis.

[14] Claiborne sailed for Kent Island on May 28, 1631, with indentured servants recruited in London and money for his trading post, likely believing Calvert's hopes defeated.

[21] The following year, the main body of Calvert's settlers arrived in the Chesapeake and established a permanent settlement on Yaocomico lands at St. Mary's City.

[24] In 1635, a Maryland commissioner named Thomas Cornwallis swept the Chesapeake for illegal traders and captured one of Claiborne's pinnaces in the Pocomoke Sound.

[25] During these events, Governor John Harvey of Virginia, who had never been well liked by the Virginian colonists, had followed royal orders to support the Maryland settlement and, just before the naval battles in the Chesapeake, removed Claiborne from office as Secretary of State.

[27] Two years later, an attorney for Cloberry and Company, who were concerned that the revenues they were receiving from fur trading had not recouped their original investment, arrived on Kent Island.

Claiborne found a new ally in Richard Ingle, a pro-Parliament Puritan merchant whose ships had been seized by the Catholic authorities in Maryland in response to a royal decree against Parliament.

[36] It also proposed to Parliament new acts which would give Virginia more autonomy from England, which would benefit Claiborne as he pressed his claims on Kent Island.

[38][18] Claiborne's legal designs on Maryland were once again defeated when Oliver Cromwell returned Calvert to power in 1653, after the Rump Parliament ended.

[42] Given the new situation, Claiborne and Bennett went to England in hopes of convincing Cromwell to change his mind but, to their dismay, no decision was made and, lacking royal authority, the Puritans gave power over to a new governor appointed by Calvert.

[43] Going behind Claiborne's back, Bennett and another commissioner reached an agreement with Calvert that virtually guaranteed his continued control over Maryland through the remainder of the Protectorate.

Claiborne therefore retired from political affairs in 1660 and spent the remainder of his life managing his 5,000 acre (2,023 hectare) estate, "Romancoke", near West Point on the Pamunkey River, dying there in about 1677.

[47] Thus, the next year, his younger son and merchant partner Thomas Claiborne (1647–1683) was noted as executor of his father's estate in a deed dated August 25, 1670 and recorded in nearby York County.

Although Leonard Claiborne (1649–1694) both received Virginia land from his father and patented 3000 acres in what became King William County, he settled in Jamaica and served in that island's assembly in 1693.