Professional historians have tended to underplay the role of individuals in shaping the destinies of humankind. In his 1961 book, What is History?, E.H. Carr famously mocked what he called the “Bad King John and the Good Queen Bess” school of history-writing. Now it is true that, as Karl Marx once said, individuals make history not in the circumstances of their choosing. They are constrained in their actions by the economic and social conditions prevailing, and in particular (so Marx argued) by technology and class relations. Nonetheless, on occasion individuals can play a vital and even determining role in shaping...