Pierse Long (1739 – April 13, 1789) was an American merchant from Portsmouth, New Hampshire. He served as a colonel of the Continental Army in the Revolutionary War and served as a New Hampshire delegate to the Confederation Congress in 1785 and 1786.
Pierse was the son of an Irish immigrant (also Pierse) who had originally traded with Portsmouth merchants from Ireland. Around 1730, he moved to Portsmouth to open a store. In Portsmouth, Pierse Sr. married and had two daughters and a son, Pierse, who was born in 1739. He died only a year or two later. Young Pierse received a limited education, then was apprenticed to another merchant, Robert Trail.
After his apprenticeship, Pierse became a merchant in his own right, exporting timber to the West Indies and importing goods from England and Ireland. He prospered in business and became active in the militia and in civic affairs.
As the Revolution neared, he became a member of Portsmouth's Committee of Safety. In 1774, he participated in the raid that removed gunpowder from Fort William and Mary. The following year, the town sent him to the revolutionary Provincial Congress held at Exeter. As New Hampshire reorganized the militia in preparation for war, he was named colonel of the Continental Army regiment raised in New Castle, New Hampshire called Long's Regiment.
During the Saratoga campaign of 1777, he led the bulk of his regiment in the withdrawal from Fort Ticonderoga. They successfully delayed the British at the Battle of Fort Ann on July 8. Very soon thereafter, their enlistment terms expired, and most of the regiment was discharged. Long and a few of his men fought as volunteers in the Battle of Saratoga as a part of Enoch Poor's brigade. But, by the end of the year, he returned home to Portsmouth. He was confined to his home for nearly half a year by illness before resuming his mercantile activities.
In 1784, New Hampshire named him as a delegate to the Continental Congress. In congress, he was active in developing some of the proposals for dealing with western lands. While not passed at the time, many of these became part of the Northwest Ordinance in 1787. On his return to New Hampshire, he served on the state council from 1786 until 1789. He was a member of the State's convention that ratified the U.S. Constitution in 1788.
Long died at home in Portsmouth on April 13, 1789 and is buried in the Proprietor's Burying Ground there.