From 31 May to 8 June 1942, during World War II, Imperial Japanese Navy submarines made a series of attacks on the Australian cities of Sydney and Newcastle. On the night of 31 May – 1 June, three Ko-hyoteki-class midget submarines (M-14, M-21 and M-24), each with a two-member crew, entered Sydney Harbour, avoided the partially constructed Sydney Harbour anti-submarine boom net, and attempted to sink Allied warships. Two of the midget submarines were detected and attacked before they could engage any Allied vessels. The crew of M-14 scuttled their submarine, whilst M-21 was successfully attacked and sunk. The crew of M-21 committed suicide. These submarines were later recovered by the Allies. The third submarine attempted to torpedo the heavy cruiser , but instead sank the converted ferry , killing 21 sailors. This midget submarine's fate was unknown until 2006, when amateur scuba divers discovered the wreck off Sydney's northern beaches.
Immediately following the raid, the five Japanese fleet submarines that carried the midget submarines to Australia embarked on a campaign to disrupt merchant shipping in eastern Australian waters. Over the next month, the submarines attacked at least seven merchant vessels, sinking three ships and killing 50 sailors. During this period, between midnight and 02:30 on 8 June, two of the submarines bombarded the ports of Sydney and Newcastle.
The midget submarine attacks and subsequent bombardments are among the best-known examples of Axis naval activity in Australian waters during World War II, and are the only occasion in history when either city has come under attack. The physical effects were slight: the Japanese had intended to destroy several major warships, but sank only an unarmed depot ship and failed to damage any significant targets during the bombardments. The main impact was psychological; creating popular fear of an impending Japanese invasion and forcing the Australian military to upgrade defences, including the commencement of convoy operations to protect merchant shipping.
Forces
Japanese The Imperial Japanese Navy originally intended to use six submarines in the attack on Sydney Harbour: B1-type submarines , , , and , and C1-type submarines and . The six submarines made up the Eastern Attack Group of the 8th Submarine Squadron, under the command of Captain Hankyu Sasaki.
On 8 June 1942, I-21 and I-29—each carrying a Yokosuka E14Y1 "Glen" floatplane for aerial reconnaissance—scouted various Australasian harbours to select the ones most vulnerable to attack by midget submarines. I-21 scouted Nouméa, Suva, then Auckland, while I-29 went to Sydney.
On 11 May, I-22, I-24, I-27, and I-28 were ordered to proceed to the Japanese naval base at Truk Lagoon, in the Caroline Islands, to each receive a Ko-hyoteki-class midget submarine. I-28 failed to reach Truk; she was torpedoed on the surface by the US submarine on 17 May. The three remaining submarines left Truk around 20 May for a point south of the Solomon Islands. I-24 was forced to return a day later when an explosion in her midget submarine's battery compartment killed the midget's navigator and injured the commander. The midget submarine intended for I-28 replaced the damaged midget.
Allies
The naval officer-in-charge of Sydney Harbour at the time of the attack was Rear Admiral Gerard Muirhead-Gould of the Royal Navy. On the night of the attack, three major vessels were present in Sydney Harbour; the heavy cruisers and , and the light cruiser . Other warships in the harbour included: destroyer tender , auxiliary minelayer , corvettes , , and , armed merchant cruisers and , and Dutch submarine K-IX. A converted ferry—HMAS Kuttabul—was alongside at Garden Island where she served as a temporary barracks for sailors transferring between ships. The hospital ship Oranje had also been in the harbour, but departed an hour before the attack.
Harbour defences At the time of the attack, the static Sydney Harbour defences consisted of eight anti-submarine indicator loops—six outside the harbour, one between North Head and South Head, and one between South Head and Middle Head, as well as the partially constructed Sydney Harbour anti-submarine boom net between George's Head on Middle Head and Laing Point (formerly known as Green Point) on Inner South Head. The central section of the net was complete and support piles were in place to the west, but wide gaps remained on either side. Material shortages prevented the completion of the boom net prior to the attack. On the day of the attack, the six outer indicator loops were inactive; two were not functioning and there were not enough trained personnel to man both the inner and outer loop monitoring stations. The North Head – South Head indicator loop had been giving faulty signals since early 1940, and as civilian traffic regularly passed over the loop, readings were often ignored.
Harbour defence craft included the anti-submarine vessels and Bingera; the auxiliary minesweepers HMAS Goonambee and ; pleasure launches converted to channel patrol boats (and armed with depth charges), namely , Lolita, Steady Hour, , Marlean, and ; and four unarmed Naval Auxiliary Patrol boats.
Prelude
The Japanese Navy used five Ko-hyoteki-class midget submarines in an unsuccessful operation against US battleships during the attack on Pearl Harbor. The navy hoped that upgrades to the submarines, intensified crew training, and the selection of a less well defended target would lead to better results and an increased chance of the crews of the midgets to return alive from their mission. Therefore, on 16 December 1941, the navy initiated plans for a second midget submarine operation.
The plans called for two simultaneous attacks against Allied naval vessels in the Indian and South Pacific oceans. These attacks were intended as diversions ahead of the attack on Midway Island in the North Pacific, with the Japanese hoping to convince the Allies that they intended to attack to the south or west of their conquests. Eleven submarines of the 8th Submarine Squadron were to carry out the two attacks, the five submarines of the Western Attack Group in the Indian Ocean, and the six submarines of the Eastern Attack Group in the Pacific Ocean. The submarine groups were to select a suitable port of attack, based on their own reconnaissance.
The Western Attack Group selected the port of Diégo-Suarez in Madagascar. This attack—which occurred at nightfall on 30 May and resulted in the damaging of the battleship and the sinking of the tanker British Loyalty—came 22 days after the British captured the port from Vichy France at the beginning of the Battle of Madagascar.
The four potential targets for the Eastern Attack Group were Nouméa, Suva, Auckland and Sydney. Identified by reconnaissance flights conducted by Warrant Flying Officer Nobuo Fujita of the Imperial Japanese Navy flying from I-25; commencing 17 February over Sydney Harbour, and the eastern Australian harbours of Melbourne and Hobart (1 March), followed by the New Zealand harbours of Wellington (8 March) and Auckland (13 March). I-21 and I-29 were sent to select the final target, with I-29 sailing to Sydney. On the evening of 16 May, I-29 fired on the Soviet merchant vessel Wellen, from Newcastle, New South Wales. Although Wellen escaped with minimal damage, shipping between Sydney and Newcastle was halted for 24 hours while aircraft and all available anti-submarine ships from Sydney, including Dutch light cruiser HNLMS Tromp, Australian destroyer and US destroyer , searched unsuccessfully for the submarine. Muirhead-Gould concluded that the submarine had operated alone and had left the area immediately after the attack.
I-29s floatplane made a reconnaissance flight over Sydney on 23 May. A secret radar unit set up in Iron Cove detected the flight, but authorities dismissed its report as a glitch, as there were no Allied aircraft operating over Sydney. The aircraft was damaged or destroyed on landing, although its two crew survived. They reported the presence of several capital ships, including two battleships or large cruisers, five other large warships, several minor war vessels and patrol boats, and prolific merchant shipping. The report, which the Allied FRUMEL signals intelligence network partially intercepted, resulted in the Japanese Navy selecting Sydney as the target. The three midget-carrying submarines rendezvoused with I-29 and I-21 approximately north-east of Sydney Heads, with all five submarines in position by 29 May.
Midget submarine operation
Final reconnaissance Before dawn on 29 May, I-21s floatplane, piloted by Ito Susumu, performed a final reconnaissance flight over Sydney Harbour, with the mission of mapping the locations of the major vessels and of the anti-submarine net. Multiple observers spotted the floatplane but assumed it was a US Navy Curtiss Seagull. No alarm was raised until 05:07, when it was realised that the only ship in the area carrying Seagulls was the U.S. cruiser Chicago, and all four of her aircraft were on board. Richmond Air Force Base launched Wirraway fighters, which failed to locate I-21 or the floatplane. Therefore, the reconnaissance flight did not result in the authorities in Sydney taking any special defence measures. The floatplane was seriously damaged on landing and had to be scuttled, but both aircrew survived.
Plan of attack The Japanese planned to launch the midgets one after the other between 17:20 and 17:40, from points outside Sydney Harbour. The first midget was to pass through the Heads just after 18:30, but heavy seas delayed her by over an hour. The other two midgets followed at twenty-minute intervals and were similarly delayed.
The choice of targets was left up to the midget commanders, with advice that they should primarily target aircraft carriers or battleships, with cruisers as secondary targets.Sasaki, Telegraphic Order 3. (Reproduced in ) The midgets were to operate to the east of the Harbour Bridge, although if no suitable targets were to be found in this area they were to move under the Bridge and attack a battleship and large cruiser believed to be in the inner harbour. When the second reconnaissance flyover revealed that the expected British battleship——was nowhere to be found, USS Chicago became the priority target.
After completing their mission, the midgets were to depart Sydney Harbour and head south for to the recovery point off Port Hacking. Four of the mother submarines would be waiting in an east–west line long, with the fifth waiting further south.
Attack Midget submarine M-14—launched from I-27—was the first to enter Sydney Harbour. The Middle Head – South Head loop detected it at 20:01, but dismissed the reading due to heavy civilian traffic. At 20:15, a Maritime Services Board watchman spotted the midget after it passed through the western gap, collided with the Pile Light, then reversed and trapped its stern in the net. The submarine's bow broke the surface; the watchman rowed toward it to determine what it was and then rowed to the nearby patrol boat to report his finding. Despite efforts by Yarroma to pass on this information, Sydney Naval Headquarters did not receive the report until 21:52. HMAS Yarroma and were dispatched to investigate. Upon confirming that the object in the net was a "baby submarine", Lolita dropped two depth charges while Yarromas commander requested permission from Sydney Naval Headquarters to open fire. The depth charges failed to detonate, as the water was too shallow for the hydrostatic fuse setting. At 22:35, while Yarroma was waiting for permission to fire, and Lolita was setting up to deploy a third depth charge, the two crewmen on M-14 activated one of the submarine's scuttling charges, killing themselves and destroying the submarine's forward section.