Oliver Hill Battery is a 9.2-inch two gun battery built on Rottnest Island in 1935 to 1939, and therefore out of period. As with De Waal Battery on Robben Island, the guns were all old British 9.2-inch Mark X guns on Mark 7 mountings. The actual barrels dated from the early 1900s, but the emplacements were all modern. The Battery therefore shows the improvements to the typical 9.2-inch British Battery, while also highlighting the many similarities with a 1900 battery of the same calibre.
The battery was part of the defences of Fremantle Fortress in World War 2. The two guns at Oliver Hill Battery were designated as H1 (East gun) and H2 (West gun). These gun emplacements are 200 metres apart, and therefore operate with their own magazines and engine room underground. There is also an underground plotting room (Battle Box) situated to the rear of the guns. The complex is linked by a narrow gauge railway.
Seven 9.2-inch batteries built in Australia during the build up to World War Two. They were:
- East Point Battery, Darwin
- Sciven Battery, Garden Island. Western Australia
- Drummond Fort, Port Kembla, New South Wales
- Banks Fort, La Perouse, New South Wales
- North Fort, Manly, New South Wales
- Fort Wallace, Stockton, New South Wales