In 1775, following the capture of the British ship HMS "Margaretta" by locals under leadership of Jeremiah O'Brien, the residents built a small breastworks here to guard the mouth of the Machias River and the area settlements. Later that year, the British sent four ships under the command of Sir George Collier that defeated the local militia, destroyed the breastworks, and burned several buildings. In 1777, the fort was rebuilt as a crescent shaped four-gun battery. In 1781 it was made part of the national defense and named Fort O'Brien. In 1808-1809, Lemuel Trescott of Eastport oversaw the construction of a blockhouse, barracks and battery. During the War of 1812, in September 1814 the British captured the fort and burnt the barracks.