Situated on the southeast end of Hassel Island, Prince Frederick’s Battery stands guard over the entrance to the harbor. It combines both Danish and British history.
A need for the battery protecting the harbor entrance had been recognized since the 1760s but was not constructed until 1778. Its plan was drawn by Lt. Peter Lotharias Oxholm in 1780.
On March 3, 1801 the battery battled a British Navy ship, preventing it from entering the harbor. Upon seizing St. Thomas on March 28, 1801, British forces incorporated the site in their fortifications, re-naming it Fort Willoughby. The structure is constructed with stones, rubble masonry and flagstone paving.
Below are further images of the site. Also, check out the American Battlefield Protection Program Grant project page for more information about the recent studies and preservation efforts at the battery.