Fort Winthrop (Boston Harbor, Governors Island, Massachusetts)

Boston Harbor, Governors Island · Massachusetts · War of 1812, American Civil War

Quick BriefFort Winthrop defended Governors Island in Boston Harbor from 1808 until its abandonment in 1905, though it saw no action during the War of 1812. A catastrophic powder magazine explosion on September 7, 1902, destroyed the fort and killed two fishermen, with the blast powerful enough to shatter windows along the North Shore. The island was filled in during the 1940s-1950s as part of Boston Logan International Airport expansion, and today Fort Winthrop lies beneath runway 14/32.

Civil WarCoastal defense

History & Significance

In 1808, the federal government acquired land on Governors Island for construction of a Second System fort, with Sylvanus Thayer, later Superintendent of West Point, overseeing its construction as an eight-pointed star. Initially named Fort Warren after Revolutionary War hero Joseph Warren, the fort was completed in 1812 just in time for the War of 1812, though it saw no action during that conflict.

In 1833, when the Army began construction on a new, larger Fort Warren on Georges Island, the Governors Island fort was renamed Fort Winthrop in honor of Massachusetts Bay Colony Governor John Winthrop. Beginning in 1846, the Army purchased the remainder of Governors Island and conducted 30 years of renovations costing an estimated $700,000.

Battery improvements were completed by 1860, completed just as the Civil War began, though Fort Winthrop saw little activity during the war and operated with only a skeleton garrison. From 1865 to 1875, ten-inch guns were replaced with larger fifteen-inch Rodman guns.

Despite extensive renovations, the fort saw minimal use as a defensive installation for the remainder of the century. On September 7, 1902, 18,000 pounds of gunpowder exploded in the fort's magazine, killing two fishermen and scattering debris across nearby islands. The Army abandoned Fort Winthrop following the explosion and relieved the last caretaker in 1905.