This thesis examines the role of Leo Amery as a military commentator and his decision to create the Army League in 1937. The League went on to argue for the introduction of conscription prior to the outbreak of the Second World War. In 1948 Leo Amery decided to resurrect the Army League and use it publicise defence issues at the beginning of the Cold War. Leo and Julian Amery attempted to shape defence policy in the late 1940s and early 1950s by using the Army League as a pressure group to influence Government policy and public opinion. It focuses particularly on the League’s report, The Army in the Nuclear Age, the culmination of several years of work by a small study group which included a considerable contribution from Basil Liddell Hart. The League published its report in November 1955 seeking to ‘educate’ the public on the key defence issues of the day including the impact of nuclear weapons on strategic planning and the need for a reorganisation of the Army. At a time when Britain was involved in two major counterinsurgency operations in Kenya and Malaya and a third was beginning in Cyprus the report also attempted to make a strategic case for retaining the remaining colonies and overseas bases at least until the end of the Cold War. However, on the contentious question of the continuing validity of National Service the League was ambiguous, proffering a solution based on utilising colonial manpower to make up any shortfall in recruitment and a reorganisation of the existing army manpower back into a small professional force with a limited conscript element. The report arrived as the Government was discussing the future of conscription and commencing a long-term defence review which meant that the League’s proposals were studied in detail by the War Office and Ministry of Defence at the behest of defence ministers. Therefore the report and the Government’s response to it add to our understanding both of the formation of defence policy immediately prior to the Suez crisis and of an alternative policy based on an aggressive response to further decolonization and anti-colonialism based on national security concerns.