Fort Winthrop (1808-1905) - A Second System Coastal Fort first established in 1808 as Fort Warren (1) on Governor's Island, Suffolk County, Massachusetts. Renamed Fort Winthrop in 1833 after John Winthrop, first governor of Massachusetts. Abandoned in 1905.
Construction was begun on 23 May 1808 by Lt. Sylvanus Thayer who later became known as the "Father of West Point". He constructed a demilune battery on the south end of the island and a star shaped fortress on the summit along with a guardhouse and powder magazine. The fort was renamed Fort Winthrop in 1833 because a larger Fort Warren (2) was being being built further out in the harbor.
The fort underwent a modernization program that started just before the U.S. Civil War that lasted until 1872. This work, along with the work on Fort Warren (2), was also supervised by Colonel Sylvanus Thayer.
Endicott Period (1890-1910)
The fort was regarrisoned for a short while during the Spanish-American War (1898) but was quickly returned to caretaker status with a single ordnance sergeant on site. On 7 Sep 1902, 18,000 pounds of powder stored in the powder magazine blew up. The cause of the explosion was never exactly determined but it was suspected that five boys had set fires on the island causing the magazine to blow up. One man was killed and five others were injured. The fort was severely damaged and was abandoned in 1905.
On 31 Dec 1909 Fort Winthrop was listed as not garrisoned and with no armament.
Destroyed by airport construction, formerly Governor's Island, Suffolk County, Massachusetts.