The suicide bomber who blew up a youth soccer match late last month left barely a dent in the hard, dry earth, and only a faint scorch on a concrete wall nearby. But he gouged a chasm of grief in the heart of the small community that lost more than two dozen of its sons in a single moment, at 6:15 on the evening of March 25. A total of 43 people died in the bombing at the game, according to figures provided by the local government. Of those, 29 were boys younger than 17 who had either been participating...