At about 23:20 on 9 July 1917 the dreadnought battleship HMS Vanguard blew up and sank at Scapa Flow. A flame was observed, followed by an explosion, more flames and smoke and a second explosion. The smoke completely obscured the ship, which had sunk by the time it cleared.
Only three of the 845 men on board were picked up. One of those, Lieutenant Commander Alan Duke, died in hospital two days later. The dead included Commander Ito, a Japanese observer with the Grand Fleet, and two defaulters from HMAS Sydney, who were being held in Vanguard’s cells. Some of Vanguard’s crew survived because they were attending
Previous posts in this series have dealt with the losses by accidental explosions of the old battleship HMS Bulwark on 26 November 1914 and the armoured cruiser HMS Natal on 30 December 1915. HMS Princess Irene, a minelayer converted from a liner, was also lost to an accidental explosion on 27 May 1915.
Several warships of other countries were also lost to internal explosions whilst in harbour during the First World War: the Italian pre-dreadnought battleship Benedetto Brin on 27 September 1915 and dreadnought Leonardo da Vinci on 2 August 1916; the Japanese battle cruiser Tsukuba on 14 January 1917 and dreadnought Kawachi on 12 July 1918; and the Russian dreadnought Imperatritza Maria on 20 October 1916. The two Italian ships were probably sabotaged by the Austrians, the Japanese and Russian ones lost to accidental explosions. The old Chilean battleship Capitan Prat was damaged but not lost by an internal explosion.
A dockyard worker called John Harston had been working on Vanguard shortly before her loss. William Schleihauf says that he had also been on board Natal before she exploded, whilst a thread on the Great War Forum says that he had also worked on Bulwark and Princess Irene. The Court of Inquiry into Vanguard’s loss took evidence from Harston and his assistant Robert Williams, concluding that there was no reason to suspect them. Harston continued to work for the Admiralty, eventually retiring with a full pension.
Schleihauf points out that Vanguard, although less than 10 years old was obsolescent because of the rapid advance in naval technology. She had 12 inch guns, whilst the latest British dreadnoughts had 15 inch guns and were larger and faster. The other British ships lost to explosions in port were obsolete. Saboteurs could have found more valuable targets that were no better guarded.
The Court of Inquiry concluded that Vanguard was lost because of a magazine explosion resulting from the ignition of cordite which could have been caused by a number of reasons: an avoidable cause; abnormal deterioration in a charge because it had been abnormally treated; sabotage by the enemy; or the cordite becoming unstable. It made 13 recommendations for improvements in handling processes and storage.
Vanguard is now an official war grave. Her White Ensign is regularly changed by RN divers. Ceremonies were held to mark the 100th anniversary of her sinking at St Magnus Cathedral in Kirkwall, Orkney, over her wreck in Scapa Flow and at the nearby Lyness Naval Cemetery, where the 41 men whose bodies were recovered are buried.
In addition to the footnoted sources, this post is based on the following websites, all accessed on 11 July 2017:
 R. Gray, Conway’s All the World’s Fighting Ships, 1906-1921 (London: Conway Maritime Press, 1985), pp. 229, 233, 256, 259, 303.
 Quoted in A. J. Marder, From the Dreadnought to Scapa Flow; the Royal Navy in the Fisher Era, 1904-1919, 5 vols (London: Oxford University Press, 1961-70). vol. iv, p. 42.