An early post-medieval coastal fort was constructed close to the Pollock Rock in Douglas Bay in the 1530s or 1540s to protect the harbour from the threat posed to Henry VIII by his continental enemies.  It is likely that Edward Stanley, 3rd Earl of Derby, would have been directly responsible for its construction. 


The fort was stone built, circular, and about 12 metres in diameter.  Curphey, in his summary of coastal defences (1967), suggests that the fort would have provided four gunports, with a guardroom and battlemented fighting platform above. The inventory prepared when the Island was surrendered to Parliamentary forces in 1651 lists three cannon and four smaller pieces of ordnance in the fort, and five more cannon outside the fort, possibly to defend it from landward assault.


The fort was partially demolished in 1818, but sufficient remained for it to appear on mid 19th century photographs and its location to be marked on the 1:2500 Ordnance Survey First Edition mapping of 1870.