A military historian who had never seen combat, John Keegan distinguished - himself a decade ago by writing The Face of Battle, a vivid triptych on three epic British battles that had all taken place within about 100 miles of one another: Agincourt (1415), Waterloo (1815) and the Somme (1916). Keegan ignored many considerations of high strategy and concentrated instead on what the ordinary soldiers had encountered through the centuries: the recurring experience of pain, noise, terror, courage, exhaustion.
Now, while quoting Montesquieu's dictum that a "rational army would run away," Keegan has undertaken a kind of sequel that shrewdly explores...