This book poses the inevitable question of how someone who has never worn a uniform, let alone fired a shot in anger, dares to write about men’s experience in battle. John Keegan’s severe polio precluded any chance of military service, yet he managed to write one of the classics of military history, The Face of Battle (1976), which dissected the experience of Englishmen on the firing line from Agincourt to D-Day. Alexander Rose, author of American Rifle (2008), now attempts to do something similar with the experience of the typical American soldier in three historic campaigns: Bunker Hill in 1775, …