Career
Sullivan read law with Samuel Livermore of Portsmouth, New Hampshire, between 1758 and 1760. He began the practice of law in 1763 at Berwick, now in Maine, and continued in the practice when he moved to Durham, New Hampshire, in 1764. He annoyed many neighbors in his early career, when he was the only lawyer in town, with numerous suits over foreclosures and was threatened with violence at least twice in 1766. But by 1772, he was firmly established and began work to improve his relations with the community. He also expanded his interests into milling from which he made a substantial income. In 1773, Alexander Scammell joined Sullivan's law practice.
Sullivan built a friendship with the royal governor of New Hampshire, John Wentworth, who had assumed the office in 1767. In November 1772, Wentworth appointed Sullivan a major in the militia. As the American Revolution grew nearer, Sullivan turned away from Wentworth and began to side more with the Patriots. On May 28, 1773, at the urging of the Virginia House of Burgesses, the New Hampshire Assembly established a committee of correspondence. Hoping to thwart the committee, Wentworth adjourned the Assembly the next day.
On December 16, 1773, colonists in Massachusetts destroyed tea worth 15,000 pounds at the Boston Tea Party to protest taxes under the Tea Act. The British Parliament responded with the Boston Port Act, effective March 21, 1774, which closed the Port of Boston until restitution for the destroyed tea was made to the East India Company. Parliament went on to pass the Massachusetts Government Act, which removed many functions of government from local control, the Quartering Act, which permitted quartering of troops in towns where there was disorder, and the Quebec Act, which established the Catholic religion and French civil law in that province.
Wentworth called a new Assembly, which began meeting on April 7, 1774. On May 13, news of the Boston Port Act reached the Assembly. On May 27, the Assembly provided for only five men and an officer to guard Fort William and Mary at Portsmouth harbor. A new committee of correspondence was selected the next day. By the time Wentworth dissolved the Assembly on June 8, in an unsuccessful effort to prevent the Assembly from sending delegates to a Continental Congress, Sullivan was firmly in favor of supporting the Massachusetts Patriots.