Skip to main content
Massachusetts State Seal
Commonwealth Museum   Secretary of the Commonwealth William Francis Galvin

Castle Island: A Beacon and a Fort


The Massachusetts Bay Colony was founded by Puritan dissidents who faced a host of potential enemies in Holland, France, and England itself.


That “a sea fort… be built, 40 feet long, 21 feet wide, for the defense of this colony.”

– General Court recommendation, March 4, 1634

Getting Started
Although granted a charter by King Charles I, the King’s advisors quickly had second thoughts about the Puritan founders and demanded the charter’s return. Concerns grew that an English fleet might arrive to dissolve the colony. A beacon was placed “on sentry hill” to give warning of approaching threats (the origin of the name “Beacon Hill.”) The colony government also decided to erect a fort. Nantasket, in present day Hull, was considered before Castle Island was selected to defend the new Boston settlement.

A painting of warships at sea
These seventeenth century English warships fly the cross of St. George. Puritans objected to the flag’s symbolism.
- Duesseldorfer

Matters of Protocol
At first the Puritan government refused to fly the English flag, which featured the cross of St. George (a red cross on a white field.) It was thought to be idolatrous, symbolizing the Church of England. After controversies with visiting ship captains, they reneged, deciding not to provoke the king. 

Still it was important that visitors identify themselves. In 1637 a warning shot struck the rigging of a ship and fell to the deck, killing a crew member. A local coroner pronounced the death due to the “providence of God.”


A portrait of John Winthrop

John Winthrop

A photograph of a column at the Massachusetts 
State House commemorates the 
warning beacon on “Beacon Hill.

A Warning Beacon

A photograph of an old document

Counterintuitive

What’s In a Name: Castle Island  
Many assume that the island takes its name from the castle like fort that occupies the site. Possibly the island’s natural topography resembled a castle when viewed from the deck of a ship. It was called “Castle Island” almost immediately.