This John Wentworth was born in Dover, New Hampshire on March 30, 1719. After service in the French and Indian War, he moved to Somersworth and was elected to the colonial assembly from 1768-1775. In that assembly he served several terms as speaker. He served as a judge of common pleas, and starting in 1776 as a justice in the New Hampshire supreme court, in spite of the fact that he neither studied nor practiced law.
As the revolution neared, he was active in the committees of correspondence, and later the Committee of Safety. After the Assembly was prorogued in 1774, a rebel counterpart met as the Exeter Convention. At their first meeting, on July 21 he was elected President.
John's son, John Wentworth Jr, represented New Hampshire in the Continental Congress. He died in Somersworth on May 17, 1781.