Ten years ago, at the Wright-Patterson Air Force Base outside Dayton, Ohio, the leaders who had waged a brutal four-year war in Bosnia -- at the center of a volatile region that had launched two world wars -- finally agreed to peace. They took this momentous step only after intense international military and diplomatic pressure led by the United States. At the time, almost everyone predicted that the Dayton Peace Agreement would fail. To enforce the agreement, I sent 20,000 U.S. soldiers to Bosnia as part of a 60,000-troop NATO peacekeeping force, because it was the only way to ensure...