HMS Royal Oak was one of five Revenge-class battleships built for the Royal Navy during the First World War. Completed in 1916, the ship 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. Royal Oak drew worldwide attention in 1928 when her senior officers were controversially court-martialled, an event that brought considerable embarrassment to what was then the world's largest navy. Attempts to modernise Royal Oak throughout her 25-year career could not fix her fundamental lack of speed and, by the start of the Second World War, she was no longer suitable for front-line duty.

The Revenge class, sometimes referred to as the Royal Sovereign class or the R class, consisted of five Dreadnought battleships built for the Royal Navy in the 1910s. All of the ships were completed to see service during the First World War. There were originally to have been eight of the class, but two were later redesigned, becoming the Renown-class battlecruisers, while the other, which was to have been named HMS Resistance, was cancelled outright. The design was based on that of the preceding Queen Elizabeth class, but with reductions in size and speed to make them more economical to build.