Fort Constitution

The fort's origins trace back to 1631 when an earthwork was built to guard against pirates. A wooden blockhouse followed in 1666. During King William's War in 1692, the site received cannons and became known as Fort William and Mary. It consisted of an earthen wall and a stone wall, which were renewed multiple times. Shortly before the American Revolutionary War, in December 1774, colonists stormed the fort to seize gunpowder and cannons – a pivotal act preceding the war. After the British withdrawal in 1775, the site was destroyed by the militia. Following the Revolutionary War, the fort was refortified in 1783 and renamed Fort Constitution in 1802. It received new walls, powder magazines, and barracks. During the Civil War, new cannons were installed, and the site was permanently garrisoned again. A planned expansion into a large fortress was halted in 1867. During the Endicott Period in the late 19th century, a new coastal battery, Battery Farnsworth, was constructed, and the harbor entrance was mined. In World War I, cannons were dismantled, and in World War II, the fort served as a mine depot. In 1961, it became property of the State of New Hampshire.

Fort Constitution is situated on a peninsula in the northeast of New Castle in Rockingham County, New Hampshire, USA. It is strategically located at the mouth of the Piscataqua River into the Atlantic, approximately 10 meters above sea level.

Visitors can explore the ruins of the fort, which date from the 19th century. The grounds are freely accessible year-round and are managed as a State Historic Site. The Portsmouth Harbor Light, electrified in 1934 and automated in 1960, remains operational.

• Fort Ticonderoga (fortress), approx. 233.0 km away
• Castle Clinton (fortress), approx. 380.1 km away
• Castle Williams (fortress), approx. 381.1 km away
• Fort Michilimackinac (fortress), approx. 1155.2 km away