Operation RIMAU: The tragic sequel to JAYWICK

Petar Djokovic

The 2009 Defence White Paper noted the need for the ADF to maintain a strategic strike capability to carry out "operations against various strategic and operational military targets". The ADF has been training for, and conducting, such operations for more than 70 years. A previous issue of Semaphore related one such successful operation, Operation JAYWICK, in which Japanese shipping in Singapore Harbour was successfully attacked in 1943. The sequel to JAYWICK, Operation RIMAU, is an example of how such operations can go tragically wrong.

The success of JAYWICK had emboldened the operation's Commanding Officer, Major Ivan Lyon, subsequently promoted to Lieutenant Colonel, into planning a larger scale attack in Singapore. The raiding party would consist of 22 operatives with an additional two peforming the duties of ‘conducting officers’. They would use 15 one-man, motorised, submersible canoes known as ‘Sleeping Beauties’ (SBs) to make their attack after which the SBs would be scuttled before making their escape in folding kayaks, known as ‘folboats’.

Six JAYWICK veterans formed part of the RIMAU party: Lyon; Lieutenant Commander Donald Davidson, RNVR; Captain Robert Page and three Australian able seamen: Walter Falls, Frederick Marsh and Andrew Huston. The majority of the others were drawn from the 2nd AIF but also included Lieutenant Bruno Reymond, RANR; Sub Lieutenant Gregor Riggs, RNVR; and Major Reginald Ingleton, RM.

The party departed Fremantle on 11 September 1944 in the submarine HMS Porpoise and arrived at Pulau Merapas on 23 September. The plan was to establish a base on the island with enough provisions to sustain the operatives for three months. Merapas is a tiny island off the east coast of Pulau Bintan and was believed to be uninhabited. A periscope reconnaissance the following day, however, spotted three Malays beside a canoe on the beach and Lyon decided to depart from the original plan; one of the conducting officers, Lieutenant Walter Carey, would remain on the island to guard the supplies.

The rest of the party re-embarked in Porpoise on the evening of 24 September for the next phase of the operation: the capture of a native boat, such as a junk, to sail the operatives towards Singapore. In the afternoon of 28 September, the junk Mustika was sighted off the west coast of Borneo and was boarded by seven of the RIMAU party. Twelve minutes later, Porpoise submerged with both vessels making their way back west. The RIMAU party, the SBs, folboats and other stores were transferred from Porpoise to Mustika on the evenings of 29 and 30 September in the vicinity of Pulau Pejantan. Once completed, the second conducting officer, Major Walter Chapman and Mustika’s Malayan crew returned to Australia in Porpoise. Mustika continued on to Merapas.[1]

Porpoise arrived safely back in Fremantle on 11 October 1944 and just four days later Chapman, along with Corporal Ronald Croton, embarked in the submarine HMS Tantalus for the rendezvous with the RIMAU party on 8 November. Tantalus, under the command of Lieutenant Commander Hugh Mackenzie, DSO, RN, was due to conduct an offensive patrol in the South China Sea.[2]

Mackenzie’s orders gave him considerable scope to exercise his own judgement in the execution of the operation. His orders stated explicitly, ‘The Commanding Officer HMS Tantalus is responsible for the safety of the submarine which is to be his first consideration and has discretion to cancel or postpone the operation at any time.’ His orders further stated, ‘Subject to patrol requirements HMS Tantalus will leave her patrol at dark on 7 November and proceed to the vicinity of Merapas Island.’ Upon arrival at Merapas, Chapman and Croton were to go ashore on the night of 8/9 November to make contact with the RIMAU party before re-embarking in Tantalus the following evening. The orders further stated ‘In the event of the pick up party and the RIMAU party failing to keep the rendezvous for the embarkation, the greatest caution is to be exercised by Tantalus, who should not hesitate to abandon the operation if contact is not re-established, or if he has some reason to suspect that the operation is compromised'.[3]

A Sleeping Beauty: a motorised submersible canoe similar to those intended to be used on the RIMAU raid.
A Sleeping Beauty: a motorised submersible canoe similar to those intended to be used on the RIMAU raid.

Mackenzie, in consultation with Chapman, decided to remain on patrol and make the rendezvous on the evening of 21/22 November. Tantalus’ main objective was offensive action against the Japanese and the orders to the RIMAU party were that they might expect to be picked up at any time within a month of the initial rendezvous date. Tantalus arrived at Merapas on 21 November and Chapman and Croton were landed at around 02:00 on 22 November. They made their way towards the rendezvous site during the night and at first light began searching for signs of the RIMAU party. What they found was not encouraging.[4]

The evidence suggested that the RIMAU party had been on the island, and had apparently left in some haste. Chapman and Croton discovered the beginnings of a large lean-to shelter in a clearing at the top of a hill, away from the original base site, with evidence that the party had been there. Empty rations tins were found scattered about; half-cooked food on ‘Commando Cookers’, fires seemingly kicked out; a few pieces of silver foil; empty cigarette cartons; among other items. Chapman and Croton estimated that the site had been abandoned about two weeks earlier. Upon returning to Tantalus that evening, Chapman and Mackenzie agreed that the operation had likely been a failure and that no purpose could be served in returning to Merapas. Tantalus arrived back in Fremantle on 6 December 1944.[5]

But what had happened to the RIMAU party? Had the delay in making the rendezvous contributed to their loss? Mackenzie conceded that that was a possibility when he wrote in his report: ‘It is to be hoped that the delay in carrying out the operation was not the cause for the loss of this gallant party, but it is, unfortunately, very possible'.[6]

Knowledge of the fate of the RIMAU party is derived primarily from Japanese sources, and many of the sources can, at best, be described as self serving.

The Malayan junk Mustika; captured for use in Operation RIMAU. (NAA: A3269, Q11/58(B))
The Malayan junk Mustika; captured for use in Operation RIMAU. (NAA: A3269, Q11/58(B))

Following the requisitioning of Mustika, the RIMAU party returned to Merapas where three operatives were disembarked to assist Carey before continuing on towards Singapore. On or around 6 October 1944, Mustika was off the west coast of Pulau Batam, and in sight of Singapore Harbour. While waiting for nightfall and preparing to launch the SBs, Mustika was approached by what was thought to be a Japanese patrol boat but was actually a Malayan Police vessel. Although there was, apparently, no order to do so, the operatives opened fire killing around four crew members while at least one escaped.

With the element of surpise lost, Lyon decided to abandon the operation and scuttled Mustika and the SBs. The operatives launched their folboats and divided into four groups to make their way back to Merapas. What ensued was a series of skirmishes with Japanese troops as the operatives island-hopped their way back to Merapas.

At least three of the groups met up again on Pulau Asore, a small island just off Pulau Mapur. There, on 16 October, they encountered a Japanese patrol for the first time. In the subsequent firefight, Lyon and Lieutenant Robert Ross were killed along with eight Japanese troops. The rest of the group escaped but Davidson and Corporal Archie Campbell had apparently been severely injured.

Their bodies were discovered by the Japanese following another firefight on Pulau Tapai. On 4 November, four days before the scheduled rendezvous, the Japanese found the operatives on Merapas. Another firefight ensued and there were more losses on both sides; Riggs and Seargent Colin Cameron were both killed.

For the next few weeks the remaining RIMAU operatives were either captured or died trying to make their escape. Eleven were eventually captured, of which one, Marsh, died in captivity from malaria. The remaining ten were held at Outram Road Gaol and tried before a military court on 3 July 1945. Their Malayan disguises, the use of Japanese identifiers aboard Mustika, and sketches and descriptions of islands and Japanese armaments all worked against them according to the Japanese records of the proceedings, and all ten were sentenced to death. The sentence was carried out at an execution ground near Passir Panjang on 7 July 1945.[7]

War crimes investigaters adjudged that no war crime had been committed as ‘By being dressed in non-military attire, these intrepid Australians voluntarily deprived themselves of the right to be treated as prisoners according to the custom and usage of war. Technically, therefore, the Japanese did not commit a war crime and, accordingly, there is no means of bringing them to justice in this particular case'.[8] In spite of this, many of the Japanese involved in the imprisonment, trial and execution of the ten were convicted of other war crimes.

The 23 members of Operation RIMAU were: Major Reginald Ingleton, Captain Robert Page, Lieutenant Albert Sargent, Lieutenant Walter Carey, Warrant Officer Alfred Warren, Sergeant David Gooley, Corporal Clair Stewart, Corporal Roland Fletcher, Able Seaman Walter Falls, and Lance Corporal John Hardy (all executed); Able Seaman Frederick Marsh (died after capture); Lieutenant Colonel Ivan Lyon, Lieutenant Commander Donald Davidson, Lieutenant Robert Ross, Lieutenant Bruno Reymond, Sub Lieutenant Gregor Riggs, Warrant Officer Jeffrey Willersdorf, Sergeant Colin Cameron, Able Seaman Andrew Huston, Corporal Archie Campbell, Corporal Colin Craft, Corporal Hugo Pace and Private Douglas Warne (all presumed killed in action).

The grave of Able Seaman W.G. Falls can be found in Kranji War Cemetery, Singapore. (Swinden Collection).
The grave of Able Seaman W.G. Falls can be found in Kranji War Cemetery, Singapore. (Swinden Collection).


  1.  ‘Technical Report on First Sortie of Operation RIMAU in HM Submarine Porpoise, Major WW Chapman, 19/12/1944.
  2. Later Vice Admiral Sir Hugh Mackenzie, KCB, DSO*, DSC, RN.
  3.  'Report on Attempted Pickup of ‘RIMAU’ Party by HMS ‘TANTALUS’, Appendix 1, Operation Order No. 44’, Major WW Chapman 12/12/1944. File [Lower South China Sea, Singapore -] RIMAU Reports Copy 1, NAA Item Number A3269, E4/C.
  4.  'Special Operations in Australia Vol. II, Part III: Operations in Borneo', Department of Defence, 1945.
  5.  'Report on Attempted Pickup of ‘RIMAU’ Party by HMS ‘TANTALUS’', Major WW Chapman 12/12/1944. File [Lower South China Sea, Singapore -] RIMAU Reports Copy 1, NAA Item Number A3269, E4/C.
  6.  'Appendix I to Report of Sixth War Patrol of HMS TANTALUS'. File [Lower South China Sea, Singapore -] RIMAU Reports Copy 1, NAA Item Number A3269, E4/C.
  7.  'Full Account of Australian Oversea Operation Party. File War Crimes - Singapore 15 - (Rimau) Execution of 10 Members Lieutenant- Colonel Lyons Party', NAA Item Number MP742/1, 336/1/755.
  8. Letter from the Minister for the Army, Mr Cyril Chambers MP to Mrs JS Hardy, 27/3/1947. File 'War Crimes - Singapore 15 - (Rimau) Execution of 10 Members Lieutenant-Colonel Lyons Party', NAA Item Number MP742/1, 336/1/755.

Sea Power Centre - Australia

Sea Power Centre - Australia
Department of Defence
Canberra ACT 2600