Originally presented by Dr Robert Nichols, the Memorial's Editor, on Friday, 31 May 2002, beside the Japanese midget submarine in Anzac Hall as part of the Roll of Honour Talks series.
Download the talk - 9:34 min (2.2Mb Mp3)
Sixty years ago today, almost to the hour, three Type A midget submarines pulled away from their large I-class "mother" submarines about 15 kilometres east of Sydney – their mission to enter Sydney Harbour and sink Allied shipping there.
The first of the two-men submarines, commanded by Lt Chuma Kenshi, entered the harbour at 8 pm. Although only the central section of an anti-torpedo boom net stretching from Georges Head to Green Point had been finished, Chuma's craft became entangled in it. It was detected by an alert harbour worker at 9:30 pm and located by harbour defence craft an hour later. Before it could be attacked, the crew, who had made repeated but unsuccessful attempts to break free, destroyed themselves and their craft by detonating its 35-kilogram scuttling charge.
Meanwhile, the second submarine, commanded by Lt Ban Katsuhisa, had slipped past the boom net and made its way to a position off Potts Point. In doing so, it was seen and fired upon around 11 pm by the US heavy cruiser Chicago and the RAN corvette Geelong. A little before this, the third midget submarine, commanded by Lt Matsuo Keiu, had entered the harbour but been immediately spotted by harbour defence craft and subjected to depth charge attack. Ban took this opportunity to fire his two torpedoes at the Chicago, which stood out against the still-illuminated floodlights of Garden Island. Both missed their target: one ran aground on Garden Island and failed to explode, but the other passed under the Dutch submarine K-9 and the depot ship HMAS Kuttabul, and struck the sea wall against which the converted harbour ferry was moored. The blast damaged the K-9 and sank the Kuttabul, killing 19 Australian and 2 British naval ratings asleep on board; 10 others were wounded.
The Allied warships started to leave port as harbour defence craft began a full-scale search for the enemy submarines. The third submarine (Matsuo's) was finally located in Taylors Bay at 5 am and attacked with depth charges. The two crew members shot themselves to evade capture.
The remaining submarine (Ban's) was never found, although a reading on an underwater electronic indicator loop at the Heads would seem to suggest that he left the harbour at 1.58 am.
That's the bare bones of the story: I want to discuss very briefly just a few aspects of it. One question can be quickly disposed of:
Were they suicide craft?
Not officially, though there does seem to have been tacit agreement among the crew members that they would not come back. Admiral Yamamoto had only agreed to the midget submarine program continuing on the proviso that arrangements be made to retrieve the crews. And, in fact, the mother submarines waited at the rendezvous point off Port Hacking for 3 days.
Why did Chuma get trapped in the unfinished boom net?
It is often alleged that Chuma tried to slip past the net behind a ferry, and inexplicably veered off at the last minute, becoming caught up in the boom net. The main evidence for this are the recordings on the inner indicator loop. It may or may not be true: Chuma may have found it difficult to keep up - being battery-powered, the submarine's speed was only purchased at the cost of range, and he may have been trying to conserve his battery power.
The midget submarines were notoriously difficult to steer, and tended to bob up out of the water. Even modern submarines sometimes find it tough-going in Sydney Harbour in broad daylight because of the currents. For Chuma, at night, in an enemy harbour, battling unknown currents, it must have been a daunting task.
Maybe we should ask not why Chuma was unlucky enough to bump into the net, but rather how the other two craft managed to avoid it.
Why did Ban miss?
The Chicago was a sitting duck. Ban had managed quite skilfully to get himself into a perfect firing position off Potts Point. (About 800 hundred metres is an ideal distance from the target since the torpedoes tend to run sluggishly at first and sink after discharge before regaining the correct running depth, which could take several hundred metres.) He was at right angles to the stationary Chicago, which was 170 metres long at the waterline – a huge target. The moon had come out and the sky was beginning to clear.
We have already noted the general problems with steering the craft. After he fired the first time, the bow of the submarine would have reared up out of the water. On board, the two men would have needed to re-trim the vessel by winding forward a moveable 406 kg counterweight. It would have taken about 2-3 minutes before they could get the bow back down, ready to fire again.
It has been suggested that the still-burning lights on the graving docks on Garden Island might have temporarily blinded Ban as he was about to fire. Then again, these lights probably helped him aim: Chicago would have been silhouetted against them. They were finally extinguished just before he fired.
Remember also that only minutes before they had been taking fire from Chicago and Geelong, and probably expected to found again at any moment.
Both men may well have been anxious, racing to do all they had to do to get the torpedoes away – perhaps they just missed.
Why do some people think that there were four submarines involved?
At around 11 pm Matsuo's sub was detected and attacked (and probably damaged) by harbour defence craft as it tried to enter the harbour. He then went to ground for about four hours, before trying again to enter around 3 am. He was spotted by Chicago – now finally leaving the harbour – who may even have collided with the submarine.
This may explain some initial reports of there being four submarines: Matsuo's submarine may have been counted twice. Indeed, the 1:58 am reading, usually taken to be Ban leaving the harbour, may also have been Matsuo.
Finally, another thing may also have muddied the waters: the plan originally did call for four submarines to take part, but an explosion on board one of them a day out from the Japanese base at Truk put paid to that.
Why do some sources give the total of the dead on Kuttabul as 19 instead of the correct figure of 21?
Some early records (from June 1942) mention 19 dead; but by 8 August the Department of the Navy is reporting 20 dead, one missing (believed dead) and 10 injured. These (understandably) inconsistent records may have caused confusion over the years, lying in archives ready to trip up the unwary.
Perhaps the real cause of the confusion is this: 19 were Australians and two were Royal Navy ratings. The British sailors may just get forgotten sometimes. Indeed, our Roll of Honour (quite correctly) only lists the Australians.
This brings me to the final point: six other men died that night.
The bodies of the four Japanese crewmen were cremated with full military honours at Sydney's Eastern Suburbs Crematorium on 9 June 1942 (the day after the shelling of Sydney and Newcastle by two of the mother submarines). Their ashes were returned to Japan.
Why did Rear Admiral Muirhead Gould, the officer in charge of Sydney's defences, give the four submariners a funeral with full military honours?
It has been suggested – quite plausibly – that this treatment was an attempt to show the Japanese how combatants on the other side should be treated, particularly important in light of the many thousands of Australians that were by then being held prisoner by the Japanese. (In any event, it proved to be a forlorn hope.)
Muirhead-Gould was much criticised for this action. In a radio broadcast, he delivered a stinging rebuke to his critics, claiming that "courage … is not the property or the tradition or the heritage of any one nation" and that "these men were patriots of the highest order".
Whether or not this action was wholly or even partly motivated by pragmatic considerations, there can be no doubting the nobility of the gesture.
A general observation
All historical events have a cause, but definitive explanations are hard to come by.
Things such as why Chuma got tangled up, or why Ban missed, or what Muirhead-Gould's motivation was we will never know for sure – though we can make reasonable conjectures. But even our best explanations will ever be tentative, though none the less fascinating to pursue. We should not expect simple explanations: sometimes there will be many reasons why something happened, as may be the case with why Ban missed. But one thing is clear: had he not, hundreds more might have died. The Chicago's full complement was around 750, many of whom would probably have been on board that night.
What is known for certain, however, is that sixty years ago tonight, 27 lives were lost on Sydney Harbour.