Winston Churchill had no doubt of the importance of studying history: “In history lie all the secrets of statecraft.” This includes its subset, leadership in war. Great war leaders, as Andrew Roberts points out, drawing on the examples of their predecessors, have the ability to make their followers “believe that they are part of a purpose that matters more than even their continued existence on the planet, and that the leader’s spirit is infused into them”. Leadership in war is morally neutral, and can be used by leaders for either the good of their nations or their destruction. To illustrate…