This book examines the structure and role of the Admiralty War Staff (Naval Staff from May 1917) from 1912 to 1918. It analyses the means by which people were recruited to the Staff and challenges the accepted view that it was the depository of the ‘nondescript’ and the ‘maimed and hurt’. It also challenges the traditional view as to both the nature of that structure and the work of the Staff during the war, and looks at the relationship that the War Staff had with other principal agents in the conduct of the war at sea: the First Lord of the Admiralty, the First Sea Lord and the Commander-in-Chief of the Grand Fleet. It analyses how that relationship changed during the war, as a result of changing personalities as well as changing bureaucratic structures and strategic realities. In particular it charts the development of the Staff especially while Jellicoe was First Sea Lord and shows that, far from continuing a system of bureaucratic centralisation, this period brought about a decentralisation of Staff work that was not simply the result of the changes that took place in May 1917. This date has normally been seen as crucial in terms of the development of the Staff as it was themoment when the First Sea Lord became de facto Chief of the Naval Staff – a position that he still holds today. Instead, this book suggests that more gradual changes were taking place which were far more significant in terms of what the Staff actually did and how they did it.