HMS Royal Oak was one of five Revenge-class battleships built for the Royal Navy during the First World War. Launched in 1914 and completed in 1916, HMS Royal Oak first saw combat at the Battle of Jutland as part of the Grand Fleet. In peacetime, she served in the Atlantic, Home and Mediterranean fleets, more than once coming under accidental attack.

On 14 October 1939, HMS Royal Oak was anchored at Scapa Flow in Orkney when she was torpedoed by the German submarine U-47. Of her complement of 1,234 men and boys, 835 were killed that night or died later of their wounds. Before the sinking of HMS Royal Oak, the Royal Navy had considered the naval base at Scapa Flow impregnable to submarine attack. U-47’s raid demonstrated that the German Navy was capable of bringing the war to British home waters. The shock of the sinking of HMS Royal Oak resulted in rapid changes to security and the construction of the Churchill Barriers around Scapa Flow.

The wreck of HMS Royal Oak is a designated war grave. It lies almost upside down in 100 feet
(30 metres) of water. The sallowest depth on the top of the hull at low tide is 4.5 metres. In an annual ceremony to mark the loss of the ship, Royal Navy divers place a White Ensign underwater at her stern.