Of the nine million people killed in the First World War, few could have died in more unusual or tragic circumstances than those lost in the Battle of May Island.
Two hundred and seventy lives were claimed as two submarines sank and three other vessels were damaged on the night of January 31-February 1, 1918.
But despite its 'battle' title, no enemy forces were involved in the disaster which happened 10 miles off the East Lothian coast.
This was the result of a series of accidents which led to 100 Royal Navy men being killed at the time and a further 170 losing their lives later.
Having lain largely undisturbed for nearly 100 years, the exact locations of those two submarines has been revealed for the first time.
Sonar images have been produced by from a survey of the Forth estuary by marine archaeologists EMU Ltd, as part of the groundwork into the proposed Neart na Gaoithe offshore wind farm. But thanks to legal protection, the wrecks will not be affected by the project.
John Gribble, a marine archaeologist, explained the significance of what has been discovered.
"The location of the two K-class subs has been known for a long time, but what's happened with this survey is that for the first time we've been able to identify which was which and we have a far better handle of the position," he said.
On the night of January 18, 1918, units of the British Grand Fleet set off from Rosyth, heading for a rendezvous in the North Sea. The formation included 19 major warships and their destroyer escorts.