The saying goes that most countries have an army, but Pakistan's army has a country. Even when it is not formally in power -- as it has been off and on for nearly half of Pakistan's 69-year history -- the Pakistani military wields tremendous influence as a kingmaker. Its leaders are no less consequential to Pakistan's political scene. Having been deposed in 1999 during his second term in office by then-Chief of Army Staff Gen. Pervez Musharraf, Prime Minister Nawaz Sharif -- now serving an unprecedented third term -- is understandably cautious in deciding who will lead the military. On Tuesday, Gen. Raheel Sharif will step down at the end of his three-year term as army chief, turning power over to his successor, Lt. Gen. Qamar Javed Bajwa. The occasion -- a significant achievement for Pakistan's government -- offers insight into the past, present and future of the country's civil-military...