Royal Australian Navy (RAN) Station 4 and Fort Skirmish


North Street, Woorim 4507

Royal Australian Navy (RAN) Station 4 co-ordinated the naval defences of Moreton Bay and also monitored anti-submarine indicator loops set between Woorim and Comboyuro Point (Bulwer) on Moreton Island, while Fort Skirmish was a two gun 155mm coastal battery at Woorim. Both sites were operational between 1942 and 1944.

RAN 4’s three surviving concrete buildings are located near the car park at the north end of North Street in Woorim. The concrete Control Post/Indicator Loop and Harbour Defence ASDIC (HDA) Control Hut is located southeast of the car park at the crest of the first sand dune. There are five main rooms plus two toilets, with entry from the west.

The single room northern concrete Engine Room is located in the undergrowth north of the car park, while the identical southern concrete Engine Room is located in a park opposite Eighth Avenue.

The only surviving element of Fort Skirmish is its northern Flank Observation Post (FOP), located next to the beach about 4.6km north of the car park next to RAN 4, accessible by 4WD with a beach permit. The FOP was originally positioned on tall timber stumps, but the concrete structure now rests on its side. Concrete footings are located nearby to the south.


Prior to the emplacement of two 6-inch guns at Cowan Cowan on the West side of Moreton Island in 1937, the coastal defence of the Moreton Bay region was based at the mouth of the Brisbane River at Fort Lytton, constructed in the 1880s.

The above defences were supplemented after the outbreak of World War II in September 1939, when two 6-inch Mk XI guns were positioned at Fort Bribie at the north end of Bribie Island in early 1940. In late 1942 two American 155mm field guns were positioned at Skirmish Point (Fort Skirmish) at the south end of Bribie Island, and in 1943 a similar battery was sited at Rous, on the east side of Moreton Island. The 155mm guns were designed by the French in World War I and were manufactured in the United States as the M1917 or M1918. In the coastal artillery role in Australia they were set on concrete mounts, where the gun’s wheels were supported on a central round concrete pillar (or 'cheese'), and the gun’s trails were traversed around a steel ring set in a concrete outer circle. Although these were called “Panama mounts” in Australia, actual Panama mounts were of a steel cruciform type.

During 1942–1943 nineteen batteries using M1917A1 155mm guns (designated by alphabetic letters and hence known as 'Letter batteries') were established and allocated to coastal defence in Australia and New Guinea. Sites in Queensland where Letter batteries were emplaced on circular concrete mounts included Skirmish Point; Rous battery; Magnetic Island in Townsville; False Cape near Cairns; and Turtle battery on Hammond Island in the Torres Strait.

Fort Skirmish was manned by ‘D’ Battery from September 1942 to May 1943, the guns arriving at Woorim on 14 September. Other batteries that were formed at Skirmish Point before moving north to Townsville included: ‘E’ Battery (formed October 1942, to Townsville that month); ‘B’ Battery (combined to form ‘D’ battery, then separated out as ‘F’ battery, sent to Townsville in October 1942, and renamed ‘B’ again in January 1943); ‘L’ Battery (formed October 1942, to Townsville December 1942); and ‘G’ Battery (raised November 1942, to Townsville in December). ‘P’ Battery was formed in November 1943, as a combined battery for Fort Skirmish and Rous.

The concrete gun emplacements (the circular concrete mounts were built atop large concrete magazines) were completed by 27 November 1943, but were not yet occupied due to modifications. By 15 Feb 1944 the base end stations (used to triangulate ship positions, and located north and south of Woorim), plotting room, gun mountings, Battery Observation Post (BOP) and Signals Operations Room (SOR) were completed. The guns were set on their new mountings on 4 and 17 March 1944, and a permanent Command Post (CP) was operational that month, but ‘P’ battery was wound up in late October 1944.

Fort Skirmish’s gun emplacements, less than a kilometre south of RAN 4, were undermined by beach erosion and were demolished in the early 1970s. The gun emplacements, BOP and the plotting room west of the guns were apparently located near the corner of North Street and Fourth Avenue. The only structure to survive is the battery’s concrete Flank Observation Post (FOP), which used to stand on timber supports, but which now lies on its side near the beach about 4.6 km north of the car park at the end of North Street in Woorim. There was apparently another FOP (or possibly the southern base end station) south of Woorim, and its remains are buried under the sand.

During World War II Moreton Bay was also protected by Royal Australian Navy (RAN) stations numbers 1 through 10. RAN 1 was a Port War Signal Station at Wickham Point, Caloundra (moved from Cowan Cowan in 1942) and RAN 2 was a Controlled Mining and Guard Loop Station which was initially located at Fort Bribie in early 1942, before it was moved to Tangalooma on Moreton Island in September 1943. RAN 3 was a Controlled Mining and Guard Loop Station at Cowan Cowan, and RAN 4 was the Indicator Loop and Harbour Defence ASDIC (anti-submarine detection sonar) Station at Woorim on Bribie Island. RAN 5 was the Combined Training Centre (Naval Wing), at Toorbul; RAN 6 was an Advanced Fairmile Base (AFMB) at Bongaree, Bribie Island; and RAN 7 was an Indicator Loop and Harbour Defence ASDIC Station at Bulwer on Moreton Island. On the Brisbane River, RAN 8 was the Boom Defence Facility, an Anti-submarine Boom across the Brisbane River between Lytton and Bulwer Island; RAN 9 was the Indicator Loop and Photo-electric Beam Station, Myrtletown; and RAN 10 was a Naval Store at Pinkenba.

RAN 4 was established in late 1942 and included a concrete Control Post, built by October, which acted as the main control position for Moreton Bay’s naval defences. It also monitored three of the four indicator loops laid between Woorim and Comboyuro Point (RAN 7) on Moreton Island, as well as two of three Harbour Defence Asdics (HDAs) south of the loops. RAN 7 controlled the remainder. Indicator loops were used to detect the presence of any submerged submarines. An indicator loop relies on the production of an induced current in a stationary loop of wire when a magnet moves overhead. If no vessel could be observed on the surface, the object detected was potentially a submarine, and a vessel could be despatched to drop depth charges. The HDAs were mounted on the seabed, and detected submarines using sonar. The indicator loops were laid between August and October 1942, and the HDAs in November and December 1942. RAN 4 was fully operational by mid November 1942, with 43 men.

There were also two concrete Engine Rooms at RAN 4, to house diesel engines to power electrical generators, and one also housed a pump. Other buildings at the site included a wardroom with officers cubicles and kitchen and shower/latrine annexes; store room; mess hut with kitchen, laundry and garage; two sleeping huts; combined bathroom and latrines; two kitchens and a shower block.

In June 1944 it was ordered that all indicator loops and other harbour defences outside the Brisbane River be removed, as the threat of Japanese attack was by now minimal, and naval defences should cease on 3 August. RAN 4 was briefly used by the Army between September and November 1944, and the Department of the Interior later auctioned off the buildings in June 1945. The timber buildings were sold, as was the Command Post, which was used as a weekender on a special lease until 1970. The building has since been restored.


Bribie Island Second World War Fortifications, Queensland Heritage Register 601143

RAN Station 9, Pinkenba (Myrtletown), Queensland Heritage Register 601448

Fort Cowan Cowan (Cowan Cowan Battery). Queensland Heritage Register 602559

Donald, Ron, 1995. Fort Bribie. The story of wartime Fort Bribie and Toorbul Point. Bribie Island RSL.

Donald, Ron, 2005. Moreton Bay Queensland in World War II, Ron Donald, Bribie Island.

Kidd, R and Neal, R. 1998. The 'Letter' Batteries: the history of the 'letter' batteries in World War II. RE Neal, Castlecrag NSW.

National Archives of Australia, Bribie Island Seaward Defences, Navy Depot 1944-1945, 60/1/1367

Walding, R. Skirmish Battery

Walding, R. Indicator Loops of the Royal Australian Navy at Bribie Island

Walding, R. Indicator Loops and Harbour Defence Asdics (HDAs)

Walding, R. Indicator Loops and Coastal Army Fortifications at Moreton Island

Dunn, P. Skirmish Battery Woorim, Bribie Island, Qld during WW2