Of the former installations, the Oliver Hill Battery and its associated railway have been preserved, remaining a tourist attraction on Rottnest Island.

[3][4] During the mid-1930s, the Australian Government upgraded its coastal defence batteries protecting the major ports of the country from enemy attack.

[9] The defence of Fremantle Port was deemed essential to national Australian security during a potential future war.

The Fort Forrest guns were moved to Swanbourne in 1938, with Buckland Hill not selected at this point because of its proximity to other vital installations.

At the start of World War II, both of the batteries at Rottnest Island and the Arthur Head and Swanbourne ones were operational.

[5][7] After the fall of Singapore and the bombing of Darwin in February 1942, Fremantle's importance increased, with it becoming the largest submarine base in the Southern Hemisphere.

In 1944, the decision was made to replace the Leighton, South Fremantle and Point Peron batteries with this type of gun.

At Leighton, work commenced in May 1945 but financial constraints prevented the completion until late 1947 and proof firing was not carried out until November that year.

The installation of these guns at South Fremantle was never completed, although work had been started, while the Point Peron Battery conversion never commenced at all.

Ultimately, while it was envisioned to have all major ports in Australia protected by dual-use 5.25-inch guns, the Leighton Battery became the only one ever operational.

Additionally, in combination with the Peron Battery, it protected the Sound from potential attacks by enemy ships approaching the island from the west.

The battery was tasked with protecting the boom net on the northern end of Cockburn Sound and was operational from March 1943.

[2] The Scriven Battery, located in the centre of Garden Island, had been part of the pre-war coastal defence plan for Western Australia but was not implemented at the time.

Unlike Oliver Hill, Scriven's construction was seriously delayed, only commencing in December 1942 and not completed until after the end of World War II.

In tandem with Oliver Hill, Scriven Battery's task was to provide long-range protection of Fremantle Harbour.

Accommodation was provided at Kingstown Barracks while supplies were unloaded at the Army Jetty and brought up to the battery via the Oliver Hill Railway.

In late 1942, a third, Southern Command, was introduced, which took charge of the Cockburn Sound batteries while the others remained under the previous system.

During the latter stages of the war, the batteries on the mainland saw an increase in Volunteer Defence Corps manning, unlike the Rottnest Island ones.

An almost 9.5 km long anti-submarine net in the shape of an arch spanned from the north-eastern end of Garden Island to Woodman Point, on the mainland.

[17][18] From Woodman Point, the barrier ran west on top of the Parmelia Bank, a sandbank stretching to Carnac Island.

Construction of this barrier started in late 1943, and it was removed shortly after the war, finding civilian use by being recycled as building material for farm sheds.

[17] The Commonwealth of Australia gave up the Buckland Hill site of Leighton Battery in 1984, handing it to the Town of Mosman Park.

The area previously occupied by the Leighton Battery was awarded to the Royal Australian Artillery Historical Society of Western Australia for the purpose of operating a museum at the site.

[5][7] In 2014, a gun shield removed from HMAS Adelaide during a refit in 1943 and dumped on a tip on the Mornington Peninsula, Victoria, was transported to Perth for refurbishment.

[9] The Oliver Hill Battery, its underground tunnels and the train ride up to it are one of the tourist attractions of Rottnest Island.