The earliest forts were built to protect the colonists. As Portsmouth Harbor’s importance increased with its Revolutionary War shipbuilding industry and the establishment of the Portsmouth Naval Shipyard in 1800, additional fortification was needed.

At Jerry’s Point there is evidence of earthwork fortification, circa 1842, and a stonework fort, circa 1873. Following the Spanish American War (1898) the improved defense of key harbors became a national priority. Fortifications such as Fort Stark were constructed on both coasts during the Endicott Period (1890-1920) and at Forts Constitution, McClary and Foster. The basic defense concept was to mine the harbor entrances and erect gun batteries. No shots were ever fired in anger.

The final coastal fortification occurred during World War II (WWII) when batteries were added to Fort Foster, and Fort Dearborn was constructed. The five remaining forts are obsolete and today are considered historic sites or parks which are open to the public. Following World War II the navy took over the army installations and used Fort Stark primarily for reserve training until the property was deeded to the state of New Hampshire in 1978 and 1983.