The mystery of HMAS AE1

Why did it dive?

The discovery of HMAS AE1 in 2017, 103 years after it disappeared without trace, solved one mystery but created another – was it sunk in action or lost due to a diving accident? Rear Admiral (Rtd) Peter Briggs lays out the evidence.

HMAS AE1 FAILED TO RETURN to Rabaul on 14 September 1914 after a day patrolling in Papua New Guinea’s St Georges Channel. There are circumstantial indications that the submarine may have come under attack, necessitating a hasty dive while its crew prepared the torpedo tubes to retaliate. Perhaps in the confusion they overlooked a crucial ventilation valve, allowing water to enter, causing a depth excursion and consequent implosion of the forward hull that crushed the submarine and killed its crew of 35 British, Australian and New Zealand sailors?

AE1 was identified on 20 December 2017, lying in over 300 metres of water off Mioko Island in the Duke of York Islands group, near Rabaul. The follow-up examination conducted aboard Research Vessel Petrel1 found the submarine lying upright on the bottom, on course for Rabaul, hydroplanes hard to rise, conning tower hatch shut, bow and stern torpedo tube caps open and the fateful clue: the ventilation valve two-thirds open.

What was AE1 doing on 14 September 1914? We are fortunate to have many of the Australian fleet’s signal and deck logs, along with reports from the fleet commander and commanding officers, to reconstruct AE1’s circumstances and movements on the fateful day. A detailed consideration of these sources is contained in a document I will refer to as the ‘Search Report 2012’.2 I am indebted to the dedicated team of researchers who contributed to this report, which will be quoted extensively in supporting the analysis presented in this article. We believe the starboard engine clutch was jammed in, preventing its associated diesel engine from being disengaged from the shaft and depriving AE1 of its starboard screw to go astern or propel when dived.3 The signal logs on the day imply that HMAS Sydney (I) had manufactured a set of bolts and sent them across to the submarine depot ship. Significantly, this defect would have deprived AE1 of 50 per cent propulsion power to recover from a flooding incident while dived.

If an attack did take place, what evidence would we expect to find when the detailed examination was undertaken, 103 years later?

3D photogrammetric model of the AE1 wreck site, showing implosion damage over the forward torpedo room and control room. From images courtesy Paul G Allen, Find AE1 Ltd, ANMM and Curtin University. © Curtin University

Lieutenant Commander Thomas Besant, AE1’s commanding officer, deviated from the orders issued to Parramatta to patrol St Georges Channel and headed northeast to the Duke of York Islands. We believe he was looking for a German steamer seen in this area by HMAS Yarra (I) the previous evening. This may have been the steamer Meklong and its tender, which were subsequently found on 23 September, well hidden in Mioko Harbour.

There is no evidence AE1 saw any sign of the steamer. From the position of its wreck site, the submarine appears to have been heading back to Rabaul, in conformance with Rear Admiral Patey’s personal direction to Besant and Warren to ‘be back by dark’. AE1 was clearly lost to a diving accident, caused by a depth excursion, which resulted in the hull collapsing (imploding) over the forward torpedo compartment and control room. A more detailed discussion of the circumstances and possibilities is included in the baseline survey report.4

Why would AE1 dive? The simplest explanation is a practice dive. As the submarines sailed on the surface from the UK, where they were built, to Australia, there would have been sound reason to undertake a practice dive whenever the opportunity presented itself. However, I think Besant’s focus this late in the day would have been the return to harbour, to repair the defective clutch. Along with the direct orders to be back by dark, these factors would have weighed against a practice dive en route to Rabaul. I believe it is highly likely AE1 completed a ‘trim dive’ after parting company with Parramatta to ensure the submarine was ready to dive at short notice and that all systems were working correctly. This was – and still is – standard submarine practice on leaving harbour. The other possibility is that AE1 crash dived to avoid attack or engagement with an enemy vessel. There are circumstantial indicators that this may have occurred. The failure to shut the ship’s ventilation valve points towards a dive in haste. Second, the outer doors to the bow and stern torpedo tubes are open, indicating the first step in preparing them for use. It is possible the preparation of both torpedo tubes may have been undertaken earlier in the day, to prepare for the eventuality of coming across the steamer sighted the night before. Alternatively, they could have been ordered open as part of a practice dive. They could also indicate that AE1 was under attack or its crew anticipated attacking an enemy vessel when it dived. If the tubes were ordered to be prepared as AE1 dived, this would have added to the crew’s workload and confusion, which may have caused the ventilation valve to be overlooked.

In his book Entombed but Not Forgotten, John Foster records a handed-down story from the Mioko Islanders, who spoke of AE1 being sighted the day it disappeared.

Where could an attack have come from?

An RAN signalman, Aubrey Hodgson,5 who temporarily served on the New Zealand steamship Aorangi, recorded an account in his diary of a discussion with Wilhelm Gustav Edwin Reuschel, an Imperial German Navy petty officer.6 Reuschel claimed to have been in charge of a yacht, the ‘colonial’ [sic], which attacked and ran down AE1. 7 This name bears some similarity to that of Kolonialgesellschaft, an armed steamer that may have been operating near the Duke of York Islands at the time AE1 disappeared. There are numerous factual errors and confused dates in Hodgson’s diary, casting doubts on its veracity. These are discussed in greater detail in Annex D of the 2012 Search Report. Nor is there any record of Hodgson’s account in the official reports of AE1’s loss. It is possible it was not deemed credible or, more likely, it was written after the events and was never considered by authorities. Reuschel was a machinist on the German vessel Planet. Some nine weeks earlier he and several other crew members were hospitalised in Rabaul suffering from typhoid. In addition to the date and other inconsistencies in Hodgson’s diary, there is no satisfactory explanation as to how Reuschel came to be on board and in charge of Kolonialgesellschaft, as he claimed. If an attack did take place, what evidence would we expect to find when the detailed examination was undertaken, 103 years later? The fin is a likely target for gunfire, given its visual prominence and presence of the bridge watchkeepers. It is plated in bronze, which remains in good physical condition today. The port side and top of the fin were examined closely during the Baseline Survey; there is no evidence of damage from gunfire. On the other hand, firing at the bridge, even if it missed, would be sufficient to cause a hasty dive to avoid being hit.

The failure to shut the ship’s ventilation valve points towards a dive in haste, rather than a more deliberate training dive

01 Ventilation valve partially open. 02 RV Petrel’s remotely operated vehicle inspecting the stern tube. Images courtesy Paul G Allen, Find AE1 Ltd, ANMM and Curtin University. © Navigea Ltd Edge of sluice valve plate

01

02

01 AE1’s fin port side, showing no signs of gunshot damage. 02 AE1’s fin starboard side (partial) and top showing no signs of gunshot damage. Images courtesy of Paul G Allen, Find AE1 Ltd, ANMM and Curtin University. © Navigea Ltd AE1 was clearly lost to a diving accident, caused by a depth excursion, which resulted in the hull imploding

Conning tower bolted flange

Conning tower wheel Conning tower access ladder

After periscope

Lower conning tower hatch opening

Opening to after fin Engine room telegraph

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02

After periscope

Forward periscope

Bridge guardrail stanchion with aftermost stanchion hanging below

Flood valve opening Conning tower upper hatch (shut)

Starboard blower/ballast pump outlet

According to the German provincial governor’s report,8 Kolonialgesellschaft was en route from Madang to Rabaul with a party of armed German Army reservists and only made it as far as Cape Lambert, 68 nautical miles to the west of Mioko Island, where it ran aground on 16 September and was abandoned. The governor’s report annexes an account provided by the officer in charge of the reservists, Lieutenant Emil Joseph Lauer.9 Unfortunately, that document has not been located. Kolonialgesellschaft was designed for an expedition to explore the Sepik River. Reports indicate that the vessel carried sufficient fresh water and coal for a voyage of 1,400 kilometres.10 Kolonialgesellschaft was armed with a one-inch Nordenfelt gun, estimated to be capable of penetrating AE1’s pressure hull from close range. On 18 September, HMAS Warrego was searching for AE1 when it came across the wreck of Kolonialgesellschaft, aground on a reef to the North of Cape Lambert. Based on the departure date from Madang of 5 September recorded in a report produced by Herr Fritz Hoyer, postmaster at Frederich Wilhelmshaven (modern-day Madang) and a military reservist who took passage on Kolonialgesellschaft, it could have been capable of reaching the Duke of York Islands; however, we have no corroborating evidence that this occurred.

Conclusion

In drawing some preliminary conclusions, it is likely that Hodgson reconstructed the account well after the events, and hence little faith can be placed in it. AE1’s crew were poorly prepared for an operational task, with little diving experience and no work-up or weapon firing training. This lends weight to the training dive/accident theory,11 but there is also circumstantial evidence of a hasty dive to avoid attack. In the latter case, the most likely candidate seems to be Kolonialgesellschaft. It had a suitable weapon and the personnel to operate it, and was rumoured to have undertaken a successful attack, but the lack of any later claim by the Germans is perhaps the most telling factor against this scenario. Lauer had reason to be quiet about his role in any attack on AE1. On capture in Rabaul he was listed as a land surveyor (his role as a lieutenant in the German Army reserves was not revealed), gave his parole and was repatriated to Germany, where he enlisted in the German Army and was killed on the Western Front.12 To my mind, questions remain: Why did AE1 dive this late in the day, en route to Rabaul? Why were two torpedo tubes partially prepared for action? Was AE1 lost in action with a German steamer, or the victim of a tragic accident? I nominate a number of research targets for future investigation to try to resolve the question: • Meklong was probably the steamship sighted by HMAS

Yarra (I) on 13 September. Could it have attacked AE1? • Are there corroborating reports from Aorangi or other ships of the account in Hodgson’s diary? • Where are the diary and report provided to Governor

Haber by Lieutenant Lauer, the officer in charge of the party on Kolonialgesellschaft? • Are there any other accounts of Kolonialgesellschaft’s performance and movements? • Are there any additional Mioko Islander stories that describe an action between AE1 and another vessel?

1 Research Vessel Petrel – Baseline Survey of HMAS AE1 (‘RV Petrel Baseline Survey’), Find AE1 Ltd and Australian National Maritime Museum, April 2018. 2 SUBSUNK HMAS AE1, 14 September 1914, Search Area Recommendation (‘Search Report 2012’), AE1 Inc, 10 February 2012. 3 AE1’s engines had no gearbox. When wishing to go astern on the surface or to propel while diving, the diesel engines had to be stopped and the engine clutches opened before the electric motors could propel the submarine ahead or astern.

4 RV Petrel Baseline Survey, Annex C, page 96. 5 Search Report 2012, para 4.7. 6 Search Report 2012, para 4.11. 7 Search Report 2012, para 4.7. 8 Search Report 2012, para 5.10.3.2. File Bundesarchiv 1001/2613 The War in New Guinea 1914 Vol. 3 see Vol 4, 15 January–15 July, which includes a report by Governor Haber on the war in German New Guinea. AIll 323/15. 9 Search Report 2012, para 4.10. 10 Source: Peter Richardson from the Bundesarchiv, 28-39-191109-30 p. 652, Expedition des Reichskolonialamtes und der Dt Kolonialgesellschaft zur Erforschung der Gebiete des Kaiserin-AugustaFlussa. Der Dampfer Kolonialgesellschaft (detailed technical description of Kolonialgesellschaft). 11 RV Petrel Baseline Survey, pages 34 and 35. 12 Search Report 2012, para 4.10.

Peter Briggs AO OAM CSC is a retired rear admiral of the Royal Australian Navy and a submarine specialist. He was chair of the board of Find AE1 Ltd, which was formed to research and lead the successful search to locate the final resting place of Australia’s first submarine. He was also a member of the expedition team aboard RV Petrel that surveyed the wreck of HMAS AE1 in 2018.