The Royal Navy, and especially its leadership, is perceived to have performed poorly in the First World War and its officers have been described as being automatons who only came alive when directed by superiors. By contrast in the Second World War the Royal Navy and its officers are seen as having ‘done well,’ displaying flair and initiative. There does not appear to have been any attempt to look in any detail at what, if anything, changed in the twenty years between the wars to explain the perceived improvement. This thesis critically examines the executive branch of the Royal Navy, and contends that the navy adapted and modified the training of its officers to meet whatever was required of them; when they were required to passively obey orders as in the Grand Fleet of the First World War, they had been trained for that eventuality, when to show initiative likewise. During the 1920s the officer corps was mismanaged and morale and motivation suffered badly. The influence of the Admiralty civil service, the repository of institutional memory, which managed junior officers’ careers, was conservative and resistant to change. Changes in training both before and after the mutiny at Invergordon (September 1931) brought the officer corps up to date and set it on track for its outstanding performance in the next war, in particular recognising that leadership was not an innate class based ability, but had to be taught and developed. However, the navy had since the latter part of the nineteenth century changed the emphasis of officer’s career paths; specialist training was seen as the ‘route to the top’ and command was downgraded as a necessary part of an officer’s career development. It was only during the latter part of Second World War that having exercised command at sea was recognised as being an important part of an officer’s experience. The thesis also addresses the ‘RNVR myth’ that the Royal Navy was only able to prosecute the Second World War successfully because of an influx of well educated temporary officers and that they were the major driving force. This thesis has been largely based on primary sources, including personnel records which have not been studied before and have been examined in such a way as to allow statistical analysis.