Dec. 21 (UPI) -- The wreckage of a lost World War I submarine used by British and allied forces has been found by the Australian Royal Navy -- ending a mystery that endured for more than a century.
The vessel carried 35 British, Australian, and New Zealand crew members when it disappeared near the Duke of York islands on Sept. 14, 1914, while on patrol for German warships.
The submarine was led by Lt. Cmdr. Thomas Besant, a 30-year-old British officer. There were no calls of distress or witnesses to the events.
Despite 13 search operations over the course of many decades, the submarine was never found -- until now.
The latest search began last week with a Dutch-owned survey vessel. The missing sub was ultimately found 1,000 feet underwater near Papua, New Guinea.
"Australia's oldest naval mystery has been solved," Australian Defense Minister Marise Payne said.
"The boat and her crew, who've been on eternal patrol since 1914 ... have now been found. I truly trust that this discovery will bring peace of mind to the descendants of the families of the crew who lost their lives."
The cause of the wreck is unknown, but it's believed the sub sank due to a technical failure -- and was not targeted by an enemy ship.
Peter Briggs, a retired admiral who led the search, said the cause of the wreck was probably due to a sudden "diving accident" and a "high energy event" -- possibly due to the explosion of one of its torpedos or a high-pressure air cylinder.
Those aboard the search vessel held a memorial for the lost crew members The exact location of the submarine is being kept secret to prevent salvage attempts.
Briggs said it is time for the "next chapter" to discover what happened to the vessel.
"It will be quite a detective puzzle," he said.