The revised and updated edition of Lt. Col. Dave Grossman's modern classic about the psychology of combat, hailed by the Washington Post as "an illuminating account of how soldiers learn to kill and how they live with the experiences of having killed." In World War II, only 15 to 20 percent of combat infantry were willing to fire their rifles. In Korea, about 50 percent. In Vietnam, the figure rose to more than 90 percent. The...