In 1776, after the Revolutionary War broke out, the Rhode Island General Assembly ordered Major Gen. Joshua Babcock to build the Conanicut Battery. The original fort was probably a simple, crescent-shaped earthwork designed to house and protect six to eight heavy cannon and their men. The British captured the fort in December 1776 and occupied it until October 1779. They rebuilt the battery in the shape seen today. A ditch surrounds the earthen barricades on all sides. The fort could house heavy cannon to defend the West Passage, and the bastions on the north and south protected it from land attack.

In July 1780, after the British left the island, the Marquis de Lafayette relayed orders to Colonel Christopher Greene, commander of the 1st Rhode Island (Black) Regiment, to load four boats with bundles of fascine sticks using 24 of his African American soldiers and “bring over those fascines to Conanicut Island, as fast as it is in your power” to reinforce the battery. At least six men in the 1st Regiment were former Jamestown slaves. French forces coming to the aid of the new United States manned the Conanicut Battery later in 1780 and 1781. 

During the 19th century, the area reverted to farmland.

In 1916, the military re-acquired the land and built six underground observation posts atop Prospect Hill, just east of the 1776 battery. From there, military observers had an unobstructed view of the approaches to Narragansett Bay and of the minefields laid in the East and West Passages during World War I and World War II. In 2023, the JHS initiated repairs to the observation posts to make them secure. 

In 1963, the federal government gave the 22-acre property to the Town of Jamestown, and in 1972 Conanicut Battery earned recognition by the National Register of Historic Places. Since the restoration of the park in 2002, the JHS has worked with the town to maintain the historic elements within the Conanicut Battery National Historic Park.