Fort Popham is a Civil War-era coastal defense fortification at the mouth of the Kennebec River in Phippsburg, Maine.

[3] These forts and batteries were built shortly after the passage of Thomas Jefferson's Embargo Act of 1807, which prohibited all exports from the US as an attempt to exert pressure on Britain and France, which had been taking actions against US shipping.

After the war four of the guns were relocated to a new battery at Cox's Head, north of Fort Popham on the west bank of the Kennebec.

It had a 30-foot (9 m)-high wall facing the mouth of the Kennebec River and was built in a crescent shape, measuring approximately 500 feet (150 m) in circumference.

During the closing months of the American Civil War, from October 1864 to July 1865, the fort was garrisoned by the 7th Unassigned Company of Maine Infantry.

[11] The back side of Fort Popham was built with a low moated curtain containing a central gate and 20 musket ports.

[12] In 1898, shortly after the Spanish–American War broke out, Congress made numerous emergency appropriations, including $3,200 to deploy the mines in the Kennebec.

It was added to the National Register of Historic Places as Fort Popham Memorial on October 1, 1969, reference number 69000012.

Henry S. "Captain John Wilson and Some Military Matters in the War of 1812", Collections and Proceedings of the Maine Historical Society, second series, 10 (1899), pp.