Fremantle Fortress, WW2 Coastal Defence Facilities - Historic Engineering Marker #9 Rottnest Island, Western Australia, Australia
By Team MavEtJu on 20-Oct-15. Waypoint GA7667

Fremantle Fortress, WW2 Coastal Defence Facilities - Historic Engineering Marker #9

In the mid 1930s the Government of the Commonwealth of Australia commenced an upgrade of its fixed coastal defence artillery batteries to protect key Australian ports from possible enemy attack.

On the west coast priority was given to establishing new facilities on Rottnest and Garden Islands and the modernising of the existing batteries on the mainland, to upgrade and extend the existing coastal defence system for the Port of Fremantle. The combined facilities were known as ‘Fremantle Fortress'.

This nomination focuses on the construction of the installations on Rottnest Island where two 9.2 inch guns were constructed at Oliver Hill and two 6 inch guns at Bickley Point. Rottnest Island is located 19 km off the west coast of Western Australia, adjacent to the Port of Fremantle at the mouth of the Swan River (see Figure 1). The waterway named Cockburn Sound extends to the south of Fremantle and lies between the coast and Garden Island. Cockburn Sound provides major harbour facilities for the Kwinana industrial strip and the Garden Island Naval Base. Garden Island is 20km south of Rottnest Island.

Of the mainland facilities the Leighton Battery at Buckland Hill was the most extensive, commissioned in 1943 and comprising two 6 inch Mark 7 guns and 300 metres of underground tunnels. It is a well preserved heritage site. The Fremantle Harbour battery comprised 2x6 pdr 10 cwt and 2x 18 pdr Mk 4 guns. The Swanbourne battery comprised two 6 inch Mark 7 guns. There were other smaller gun installations on the north mole of Fremantle harbour, at South Beach and at Point Peron, south of Fremantle.

The Garden Island facility consisted of two 9.2 inch guns, two 4 inch ex-US naval guns and 2x155 mm guns.

Construction of battery installations at Oliver Hill (2 x 9.2 inch Mark 10) and Bickley Point (2 x 6 inch Mark XI) on Rottnest Island commenced in 1935. At the outbreak of WW2 the system had been enhanced by the batteries on Rottnest Island. During the war, additional batteries were installed on Garden Island, Fremantle Harbour, Leighton and Swanbourne (north of Fremantle) and Point Peron (south of Garden Island). The extent of coverage afforded by the Fremantle Fortress batteries is illustrated in Figure 2. The inner approaches to the Port of Fremantle were well protected. However, the island facilities, and in particular the Rottnest Island batteries, extended that range well out to sea in order to protect against potential damage to the Port delivered by ship-borne long range guns.

STATEMENT OF SIGNIFICANCE

The Rottnest Island WW2 Coastal Defence Facility is the only intact establishment remaining in Australia of the seven 9.2 inch coastal gun batteries constructed during the late 1930s and early 1940s to defend key Australian ports when there was a real threat of invasion by hostile enemy forces. It is one of a very small number of 9.2 inch gun batteries remaining in the world.

The Port of Fremantle played a vital role in Australia’s involvement in WW2, being a major base for American, British and Dutch submarines, a troop convoy assembly point, a shipping repair facility and a bunkering port. The Rottnest Fortress, as it was known, had a major deterrent role in the defence of Fremantle against possible seaborne enemy attack. Fremantle Fortress.

The construction of infrastructure for and the installation of high precision military equipment, in difficult circumstances, was a significant technical achievement. For the thousands of ex-service men and women who served on the island up to and during the WW2 years the facilities have considerable social significance.

When logging this virtual, please add a photo of yourself or your GPSr at the plaque.

For more information, please see this page at the Heritage Register at the Engineers Australia website: https://www.engineersaustralia.org.au/portal/heritage/fremantle-fortress-ww2-coastal-defence-facilities-1940