It is one of the many Palmerston Forts built on the island to protect it in response to a perceived French invasion.

It was a replacement of the earlier Sandown Diamond Fort as, in 1859, the Royal Commission felt it did not offer suitable protection.

[2] The fort was sold in 1930 but during World War II the fort played a significant role in the D-Day landings as it housed sixteen pumps for the PLUTO (Pipe Line Under The Ocean) operation to keep the Allied forces supplied with fuel.

Each of the 16 pumps supplied 36,000 imperial gallons (1,000 barrels; 160,000 litres) of fuel per day at a pressure of 1,500 pounds per square inch (100,000 millibars).

[1] In the 1950s the site was used to house the Isle of Wight Zoo, which was renamed as the Wildheart Animal Sanctuary in 2021.