Fort Constitution, New Hampshire — History & Visitor Guide

Fort Constitution (New Castle, New Hampshire)

New Castle · New Hampshire · Revolutionary War, War of 1812, Spanish-American War, World War II

Quick BriefFort William and Mary was a colonial-era British fortress on the island of New Castle, at the mouth of the Piscataqua River in the Province of New Hampshire. During the American Revolutionary War it was captured by rebel forces, recaptured, and later abandoned by the British. Following an 1808 rebuilding in response to increasing British hostilities, it was renamed Fort Constitution and served in the War of 1812. The fort site was given back to the State of New Hampshire by the American military in 1961 and turned into a state park. It was listed on the National Register of Historic Places in 1973.

Coastal defenseOpen to visitors

History & Significance

Originally known as "The Castle," this fortress at New Castle guarded Portsmouth Harbor beginning before 1632 and was renamed Fort William and Mary circa 1692 after the accession of William III and Mary II to the British throne. The fort initially served as the colony's main munitions depot.

On December 14–15, 1774, the fort was raided twice: a large group of patriots led by John Langdon overpowered a six-man caretaker detachment and confiscated much of the fort's gunpowder supply; on the second night another raid under John Sullivan seized 16 of the fort's cannon and muskets. These raids were the first acts of the Revolution in New Hampshire.

Following the Revolution, New Hampshire gave the ground to the federal government in 1791, and in 1800 the Portsmouth Naval Shipyard was established upriver. Brick masonry walls were doubled in height and new brick buildings were added inside; work was completed in 1808 and the defense renamed "Fort Constitution."

During the War of 1812, the fort was manned and expanded, including the addition of Walbach Tower, equipped with a single 32-pounder cannon, constructed in 1814. Another rebuilding and expansion was carried out in the wake of the Spanish-American War in 1899.

The fort served actively through the first half of the 20th century and World War II. In 1940–1944 the Harbor Defenses of Portsmouth were garrisoned by the 22nd Coast Artillery Regiment of the U.S. Army. The Fort Constitution site was given back to the State of New Hampshire by the American military in 1961 and turned into a state park.

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🧳 Visiting

What you’ll see when you visit:

Colonial-era stone fortifications at the mouth of Piscataqua River
Views of Portsmouth Harbor from defensive positions
Historical narrative spanning Revolutionary War through World War II
Restored structures demonstrating 17th-19th century military architecture

Best time to visitSpring (May-June) and fall (September-October) offer mild weather; summer can be warm and humid along the New England coast.

Getting thereNearest airport is Portsmouth International Airport at Pease (PSM), about 9 km from New Castle.

From the nearest major airportPortland International Jetport (PWM)🚗 52 mi by road⏱️ ≈ 1 hr 11 min drive

Fort Constitution (New Castle, New Hampshire)

History & Significance

Key Facts

Map

🧳 Visiting

Sources

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