Fort O'Brien

Fort O'Brien is a historic military post along the Machias River in Machiasport that today shows earthen ramparts, a flagpole, and ruins of coastal defense structures. The two-acre grounds display the layers of construction and destruction that occurred over its long use.

The fort was built and destroyed three times between 1775 and 1863, serving as a defense post during the Revolution, the War of 1812, and the Civil War. This pattern of reconstruction shows how the location remained strategically important for coastal protection throughout these conflicts.

The site reflects local efforts to defend the coast against invasions across different eras of American conflict. Walking through the grounds today shows how this place remained important to the region through multiple wars.

The grounds are open to visitors from late May through early September, with parking available near the riverbank. Wear good footwear since the terrain is uneven in places and consists of grass and earth.

A twelve-pound Napoleon cannon from the Civil War period still stands at the site, showing the final military setup of the fort. This gun is one of the few surviving original weapons on the grounds and catches the eye of most visitors walking through.

Location: Maine

GPS coordinates: 44.68944,-67.39667

Latest update: December 13, 2025 12:24