In early 1917, the First World War had been going on for two and a half years. Despite the disappointing outcome of the Battle of Jutland the previous year, the British Grand Fleet, consisting of battleships, cruisers, and destroyers and based in northern Scotland, was successfully confining the German surface navy to the German Bight, while enforcing a blockade of German maritime trade with the wider world. In southern North Sea, the Harwich Force and the Dover Patrol, both consisting of cruisers and destroyers, maintained control of the eastern approaches to the English Channel and the Thames Estuary and safeguarded British communications with France. German submarine attacks on British trade became increasingly effective during the autumn of 1916, and unrestricted submarine warfare was soon to begin; finding effective countermeasures was increasingly taxing for the Admiralty. In the Mediterranean, the Royal Navy provided support to the French and Italian Fleets countering the threat posed by the Austro-Hungarian and Turkish fleets. All of these diverse naval commitments placed huge demands on the Royal Navy's resources; in particular, the need for large numbers of destroyers was pressing.