On 14 October each year, a White Ensign is placed on the stern of an upturned warship by Royal Navy divers. This act commemorates the 835 men of HMS Royal Oak who died in 1939 when the battleship was sunk at anchor in Scapa Flow by the German U-boat U-47. The sinking of the veteran First World War Revenge-class Royal Oak shocked not only the Admiralty, but the whole nation. Though Scapa Flow was far from being impregnable as a base for the Royal Navy's Home Fleet, it was surrounded by a ring of islands separated by shallow channels subject to fast-racing tides. While it was recognised that it was not impervious to enemy submarines, measures had been put in place to minimise any such threat. Blockships had been sunk at potentially vulnerable points and anti-submarine booms deployed across the wider channels. The outbreak of war in September 1939 saw additional anti-submarine measures put in hand. Despite these increased precautions, German aerial reconnaissance had spotted weaknesses which were exploited on the night of 13/14 October 1939, by Kapit nleutnant G nther Prien in U-47. The German submarine was able to slip into Scapa Flow undetected and fire three torpedoes towards Royal Oak. Only one torpedo found its mark. A second salvo was fired and this time all three hit the battleship, igniting a magazine causing massive damage. Within thirteen minutes, HMS Royal Oak had turned over and sank. In Faces of HMS Royal Oak, Dilip Sarkar not only reveals the tragic and moving stories of many of those who died, but also some of the 399 who survived the sinking of the first Royal Navy battleship lost in the Second World War. Through their photographs, and in some cases words, the horrors of those fateful few minutes as Royal Oak rolled and slid into the cold, dark waters of Scapa Flow, are relived in startling clarity.