Perry O'Brien went to war. Then he said no. America's campaign against the spread of terrorism has been divisive over the last three years, beginning with the invasion of Afghanistan, the hunt for Osama bin Laden and later the war in Iraq. It has split families and friends, become fuel for media pundits and classroom discussion, and made soldiers out of another generation. Perry O'Brien, 22, has the kind of background typical of soldiers in today's military: He's from a good family, is full of ideas and wants to serve his country. In another way he's not so typical. Three...