The haunting discovery of the watery graves of long lost Australian, German and Japanese sailors has uncovered vital clues to two World War II mysteries.
The 66-year-old secrets of two of Australia's strangest wartime naval encounters have been at least partially revealed through the location of three sunken ships over the past 18 months.
In November 2006, a Japanese midget submarine involved in a daring raid on Sydney harbour in the heart of the nation's biggest city was found off the beach of the Pacific east coast.
The sub is believed to be the tomb of its two-man crew, which disappeared after its May 1942 mission killed 19 Australian and two British sailors in a torpedo attack on the Australian ship HMAS Kuttabul.
Then, earlier this month, the first eerie photographs surfaced of the Australian cruiser HMAS Sydney and the German raider Kormoran, which both sank after a battle off the west coast that had baffled historians for years.
All 645 men on the Sydney went down with the ship in November 1941. On the Kormoran, 81 sailors died while 317 survived to give the only eyewitness accounts of what happened.
While Australian troops were heavily engaged on battlefields abroad during World War II, attacks such as these around their remote home continent were rare and shocking.
Bracketing a deadly Japanese air raid on the northern city of Darwin in February 1942, they heightened fears of invasion.
"The Japanese sub attack was significant as Sydney was so far away from the main theatre and the Japanese were able to come this far south and launch an attack on our largest city," says Australian National University's David Horner.
"You've got to remember Australia had a population of seven million people in World War II, so we felt very vulnerable. There was a real legitimate concern in early 1942 that Australia might be invaded," Horner told AFP.
The midget sub was one of three that slipped into the harbour on the night of May 31 1942 after being launched from a fleet of larger submarines offshore.
Two of the midget vessels were spotted and attacked, leading the two-man crews to commit suicide, Australian national archives record.
But the third sub, M24, managed to fire two torpedoes at the US heavy cruiser USS Chicago, one of which exploded beneath the HMAS Kuttabul.
The submarine then slipped out of the harbour, its mission complete, but historians long argued about whether it managed to make a complete escape.
The mystery was solved when a group of amateur divers discovered the vessel upright on the seabed in deep water about five kilometres (3.1 miles) off Sydney's northern beaches.
"The submarine is of international historical significance and is presumed to still contain the remains of its commander and navigator, Sub-Lieutenant Katsuhisa Ban and Petty Officer Memoru Ashibe," the government said.
The authorities decided the bodies would remain undisturbed on the seabed in their craft, which has been declared protected under Australia's Historic Shipwrecks Act.
The discovery of HMAS Sydney was announced by Prime Minister Kevin Rudd on March 17, reopening a national wound inflicted by a converted German merchant ship on the pride of the Australian fleet.
The final moments of the World War II cruiser had mystified historians who puzzled over why searchers had been unable to find any survivors or debris from the massive ship.
The only witnesses, the surviving German sailors, said the badly damaged Sydney was last seen steaming over the horizon after the battle that took place some 112 nautical miles off Australia's west coast.
Many Australians doubted the truth of the German version, giving rise to several dark conspiracy theories.
These included suggestions that the cruiser was in fact attacked by a Japanese submarine, that it sank hundreds of miles (kilometres) from where the Germans said it had, and that survivors were machine-gunned in their lifeboats.
But the location of the Sydney and images of the enormous damage inflicted on the ship proved that information provided by the German survivors was accurate, said naval historian David Stevens.
"No one has discovered anything that shows the German survivors were lying about what happened," he said.
Australians had simply found it difficult to accept that the nation's major warship should have been beaten in battle by a smaller, converted merchant vessel.
"We keep portraying ourselves as a people who can punch above their weight, who've got extremely good warriors," Stevens said.
"That's fine as a legend for building up our own pride but in reality the other nations are doing exactly the same thing. We are not inherently better at fighting than anyone else. That's difficult for people to accept."
But in war the element of surprise is vital, and the captain of the Sydney left his ship vulnerable by approaching too close to the Kormoran before it dropped its merchantman disguise, raised its battle flag and opened fire.
"The simple answer is he got too close. What we don't know is why he got too close," Stevens said.
The evidence provided by the wreck, which was found at a depth of some 2,470 metres (8,150 feet) about 12 nautical miles from where the Kormoran had been discovered a day earlier, also explained the lack of survivors, he suggested.
"The wreckage has shown it was extremely badly hit, both on the upper decks and through the hull. There must have been huge carnage. They might not have had a chance to abandon ship. There might not have been people alive on board."
As for the midget submarine, speculation would suggest it either arrived late for its rendezvous with the mother sub after carrying out its deadly raid or ran out of power on the way, Stevens said.
The wreck has been declared protected and has not been entered to establish exactly what happened.
But navy divers collected sand from the site to present to Japanese relatives who joined their former enemies at an emotional ceremony honouring the two sailors over their wartime graves in August last year.
And on April 16, initial memorial services attended by Australian and German officials and relatives of the Australian victims were held above both the HMAS Sydney and the Kormoran.
They will also be left undisturbed. (AFP)