Fort Doyle was originally completed in 1805 during the course of the Napoleonic Wars . Although called a fort, it was to all intense and purposes a coastal artillery battery. There was a dry ditch to cut the Southern approaches to the Fort from the main Island and this was covered by two small caponiers.
By 1816 Fort Doyle mounted three 18-pdr SB guns on garrison carriages. By 1842 the proposal was for one gun on a traversing carriage and one other on a garrison carriage. By 1860 the two flank guns had both been mounted on wooden traversing platforms to increase their arcs of fire. By this time the guns had probably been upgraded to 24-pdrs or 32-pdrs. By 1900 Fort Doyle had become redundant and in 1909 was converted for use as a navigation light and foghorn.
The site was further modified during World War 2 when the Germans had their own coastal defence battery at this location.