The date is 28 September 1939. The author cannot know that what he will record in this 15-shilling notebook – and the many that follow it over the next six years – will become an astonishing first-hand account of Britain’s darkest hours, and a vivid, often harrowing portrait of one of its greatest leaders. For this is an extraordinary soldier, General Sir Alan Brooke, later Field Marshal Lord Alanbrooke, destined to become Churchill’s right-hand man as head of the British armed forces, and broker of the Grand Alliance with Roosevelt and Stalin. Yet despite the pivotal role he played, his name is still comparatively little known.