As the war in Iraq is debated and turned into history, the emphasis will be on the role of technology -- precision bombing, cruise missiles, decapitation strikes. That was what was new. But there was another side to the war, and it was the one that most of the fighting men and women in Iraq experienced, even if it wasn't what Americans watching at home saw: raw military might, humans killing humans. The Third Battalion, Fourth Marines was one of the rawest expressions of that might. Based in Twentynine Palms, Calif., it specializes in desert warfare, and its forces number...