Who Will Rule?

At the high-walled villa of Afghan warlord Gul Agha Shirzai, the horse trading has already begun. On the edge of a magnificent carpet in his vast reception room, Shirzai holds court daily, propped against a bolster, surrounded by whispering attendants and discreetly armed bodyguards. For the past month, a steady stream of low-level tribal leaders from across the border in Afghanistan has appeared at his ornate doors in Quetta, Pakistan, seeking an audience with a man they expect will soon return from a five-year exile. His contacts and prominence—Shirzai heads an ancient and powerful clan—make him a strong contender to replace...