When today's world leaders need inspiration and strength in times of crisis, they often turn to Winston Churchill, quoting him and citing his heroic example. The son of a member of Parliament, Churchill, a poor academic student, wanted to be a soldier early in life. But after he escaped from a South African prison camp, his national fame catapulted him into a life of politics. In this Penguin Life, the eminent historian John Keegan charts Churchill's...