93 years ago today, on the 9th of July 1917, over 800 lives were lost when HMS Vanguard blew up in Scapa Flow. Fortunately, some lives were saved as several officers were attending a Concert on HMS Royal Oak, many of the crew had been lent for duty on other ships and 40 of the usual occupants were on leave.
All but three of the men who were left aboard survived the explosion. One, an officer, was retrieved from the water in his pajamas but he was very badly burnt and did not survive. Two others, a stoker and a marine, were in hammocks on the deck and were not badly injured but had seen nothing to help the resulting enquiry into how the detonation had occurred.
The first thought was that a U-boat had entered the flow but this theory was quickly discounted and it became apparent that some cordite that had been inside the ship had caused the blast. It was discovered that the heat of the ammunition's storage units had perhaps not been checked as often it they could have been, but foul play was also suspected.
It was noted in the enquiry that "it would be a comparatively easy matter to introduce some device, with delay action, into the tube of a magazine, which would cause an explosion or generate great heat in the magazine." The results of the enquiry were inconclusive.