In September 1939 and throughout most of the Second World War, Cecil’s authority over the work of the League of Nations Union (LNU) remained strong. Despite his advancing years, Cecil remained energetic. He was optimistic about the ability of a modified League of Nations to shape the post-war settlement when peace came, a view that he shared with the majority of peace activists. Indeed, an examination of their correspondence reveals that they did not view the League as a ‘failure’ because it had not prevented the outbreak of a second major European-based war. To Cecil, the war was merely a serious setback towards the achievement of the longer-term strategic goal of world peace. Furthermore, as the war progressed, Cecil believed that this was the way that the League was viewed internationally. The final two decades of Cecil’s life also offer a means of evaluating his views on wider strategic issues, such as European economic integration and the future role of the emerging superpowers in preserving international security. By 1945, Cecil believed himself too old to lead the debate within the LNU on these issues any further and made preparations to make way for a successor. Yet his gradual retirement led to little diminution in his status as the most prominent international peace activist of his generation. Cecil took as great an interest in the dynamics of Cold War diplomacy as he did in the transformation of the League into the United Nations.