Breakwater Fort was was built on the recommendations of the Royal Commission 1865. It was also called Fort Head (North Head) or Fort Chequers. The foundations were a granite base for stability and this was 12 feet above the high water mark. The fort was built between 1868 and 1875. The gun level was built to mount fourteen 12.5-inch RML guns behind an iron shield. The shielded sided were similar to the Solent Sea Forts and Breakwater Fort in Plymouth. The magazines were under the gun deck.
There was consideration given to two levels of guns, and also armoured turrets, but cost constraints saw this ideas shelved.
The initial armament was only seven 12.5-inch RMLs, and although numerous proposals were made to upgrade the armament nothing was done until 1898. In that year two 12-pdr guns were mounted on the roof, to supplement the other two 12-pdr QF guns on the Breakwater.
In 1907 two 6-inch BL guns were mounted on the roof of the fort.
Report indicate that a Whitehead Torpedo Station was built in the foundations of the Fort, but this has not been confirmed.