extract from Corvette Magazine

 

Wallaroo’s Submarine Attack

 

ON 14 JULY 2012 a short letter was received from Mr Les Heap of Lane Cove providing brief information, which may be historically significant, on the Bathurst Class minesweeper HMAS Wallaroo before she was commissioned. Mr Heap believes he may now be the last person alive who served in Wallaroo on 1 June 1942, the day after the Japanese submarine raid on Sydney Harbour. Accordingly, he would like his memories of this event recorded.

 

Further investigation reveals the following story as outlined by Les. During WWII he served his apprenticeship as a fitter and turner with the shipbuilder Poole and Steel at Balmain. He was involved in building and preparing engineering machinery fitted into the new ship Wallaroo. When a fourth-year apprentice aged 20 he, with a number of other apprentices, formed part of the crew of Wallaroo when she was engaged in trials involving day running from Balmain to outside the Heads where the ship and her equipment were trialed.  

 

A Japanese submarine raid on shipping in Sydney Harbour occurred on the night of 31 May 1942 when M-24, one of three midget submarines, fired two torpedoes. One narrowly missed the cruiser USS Chicago and sank the accommodation vessel HMAS Kuttabul resulting in the loss of 21 lives. M-24 escaped out of the harbour and was not relocated until 2006 when her remains were discovered in 55 meters of water off Bungan Head on Sydney’s northern beaches. On 1 June 1942 Wallaroo continued with her normal routine conducting shipbuilder trials day running outside the Heads. She had a mixed crew of mostly dockyard employees with some naval personnel. The ASDIC operators were naval ratings and on this particular day, for the first time she carried live explosive depth charges with a naval rating in charge.

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Also on board was Hugh Poole, a grandson of the Managing Director of the yard; his aunt Mrs Poole had launched the ship. The ship left her berth at Balmain as normal at 0730 and the crew was well aware of the activity that had occurred the night before, with enemy submarines entering the harbour. Les is unsure if this is the reason why live depth charges had been taken onboard as previously she had carried dummy charges filled with sand. He described these as drums a bit smaller than the universal 44-gallon type, which were too heavy to lift. They were rolled into the port and starboard depth charge throwers situated at the after end of the ship and then launched overboard.

 

Les was one of six apprentices onboard on 1 June and later that morning when cruising off Bondi he was detailed to assist with the depth charges. At about 1100 the Bridge informed the ship’s company that they had an ASDIC contact and the ship was going to stop and that all noise onboard was to cease. They then re-started the engines and engaged with live charges, with about 10 charges released over a period of about one hour. The detonating charges produced plumes of water rising to about 20 feet. After this nothing further was heard on the ASDIC and the ship reverted to her normal routine, returning to her berth about 1700. From talk onboard, the ASDIC operators were said to be sure they had heard the noise from a small propeller beneath their ship and at this time there were no other contacts or ships visible. Les says as far as he is aware none of the shipyard staff who crewed the ship that day were questioned on this event and over time the incident was forgotten. 

 

When the wreck of M-24 was discovered in 2006 Les was reminded of this incident and wondered if indeed depth charges from Wallaroo had affected the watertight integrity of the midget submarine causing her to sink. He has since been endeavouring to find someone to take interest in his story but the sources he has used have so far discounted it.

 

It is of note that the Royal Naval Type D, later known as the Mark VII, depth charge fits the description given in this story. These had a 120 lb charge which could be set to explode at 40 or 80 feet and these were normally released from depth charge throwers.

 

The above was related to Steven Carruthers, an ex-RAN anti-submarine warfare specialist who later worked as a commercial diver before taking up writing. Steven has conducted an extensive study of the Japanese submarine attack on Sydney Harbour and has written two books on the subject. Steven has provided the following response. ‘I do not dismiss the notion that Wallaroo was involved in an action outside Sydney Heads on the morning of 1 June 1942. However, given that Wallaroo did not leave her berth at Balmain until 0730 hours, her ASDIC contact could not have been a midget submarine.

 

On 31 May 1942, sunset was at 1654 hours. We know that the midget submarines were released from their carrier submarines between 1600 and 1630 hours about 9 km (4.8 nm) from the harbour entrance. The loop readings show an outward crossing at 0158 hours on 1 June, which was Sub-Lieutenant Katsuhisa Ban and Petty Officer Mamoru Ashibe in M-24 leaving the harbour.

 

These craft operated between 2 and 4 knots, which allowed them to operate inside a harbour for about 12 hours. Higher speeds reduced their endurance greatly. At a top speed of 19 knots underwater and a surface speed of 24 knots, their endurance was only 55 minutes, less than an hour.

 

If we consider that M-24 was the last craft to launch from its carrier submarine (I-24) at 1630, then 9.5 hours had elapsed when M-24 crossed the indicator loop at 0158 hours. This left about 2.5 hours endurance before her batteries would have been exhausted. M-24 would have been dead in the water around 0430 hours on 1 June 1942, long before Wallaroo left her berth at Balmain at 0730 hours.

 

From when M-24 was sighted by HMAS Geelong at 2310 hours, it appears M-24 sat on the harbour floor before firing her torpedoes at 0030 hours. Given this extra hour, M-24’s batteries still would have been exhausted before Wallaroo left her berth. It is more likely Wallaroo detected one of the parent submarines searching the coastline for signs of the midget submarine crews, probably I-21. Captain Hankyu Sasaki records that he was at the harbour entrance during the night and observed searchlights inside the harbour. It is unlikely that more than one submarine was in this sector without risking an underwater collision –multiple submarines in the same sector would have been the same as flying aircraft at the same altitude, an unacceptable risk for any submarine commander.

 

Editor’s Note: As Wallaroo was not in commission at this time there is little information contained in naval historical records to substantiate this story, however, other than it seems strange that it has taken such a long time to come to notice the story related appears perfectly credible. Owing to the unusual circumstances and confused state in Sydney Harbour at this time Wallaroo could well have been provided with live depth changes mainly for her own protection. While Rear Gerard Admiral Muirhead-Gould, DSC, RN, the Flag Officer-in-Charge at Sydney makes no mention of this incident in his report of the submarine attack, the report is now generally regarded as being deficient in a number of instances, so this is not necessarily remarkable.  On 5 August 2012 I had the pleasure of meeting with Les, who as an eye witness to the event was not entirely convinced with the answers provided. His theory involves two points: firstly, that the close ASDIC contact was of a small propeller and therefore unlikely to be that of a large submarine and secondly, the intended rendezvous for the returning midgets to their parent vessels off Port Hacking would take M-24 south of Sydney.

 

An ASDIC contact however is only able to measure return echoes and is unable to detect or differentiate types of propeller noise. He maintains M-24 did proceed south and rested on the sandy bottom off Bondi waiting for the best time to make the rendezvous with her mother ship. When discovered by Wallaroo she then tried to make her escape to the north drawing her attackers away from the rendezvous and thereby sacrificing herself for the greater good. As we know by this stage M-24 had minimal battery supplies this scenario therefore appears doubtful. The exact outcome however is likely to remain one of our great maritime mysteries. Wallaroo had an unfortunate short life. She was commissioned on 15 July 1942 and saw service patrolling and providing escort duties and minesweeping duties between Adelaide and Fremantle. Just after midnight on 11 June 1943 while at sea off Fremantle she collided with the United States merchant ship Henry Gilbert Costin. The night was overcast and as a precaution against attack both ships were darkened and steaming without lights. Three of Wallaroo’s crew were killed in the collision and she sank four hours later. The merchant ship suffered little damage and reached port safely.

                                                                                                                                                Source: Naval Historical Society  

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