In the summer of 2003, the "Bulletin of the Atomic Scientists" published an essay warning that the United States was on the verge of losing the peace. Dozens of similar arguments appeared that year, but this one, written by Michael V. Bhatia, a 26-year-old graduate student, was as devastating as any of them. In 2007, to the surprise of some of his friends, Mr. Bhatia joined one of the U.S. military's most visible efforts to fix its mistakes. In October he flew to Afghanistan to join the Human Terrain System, a controversial program that places social scientists in Army brigades. This article provides a profile of Michael V. Bhatia, a peacekeeper and scholar who was killed by a roadside bomb in eastern Afghanistan while participating in the Human Terrain program. Friends and colleagues are still trying to come to terms with Mr. Bhatia's death. At the age of 30, he had already published one book and completed work on another. He had several other projects in the works, and he had lined up a visiting professorship at the University of Tromso, in Norway. That position would have allowed him to finish his dissertation for the University of Oxford--a study of the demobilization and disarmament of militias in Afghanistan, a country he knew well. In December he wrote to a friend that he had "one chapter left to write, two to revise."