Afghanistan has been a strategic prize for foreign empires for more than 200 years. The British, Russians, and Americans have all fought across its beautiful and inhospitable terrain, in conflicts variously ruthless, misguided and bloody. This violent history is the subject of David Loyn's magisterial book. It is a history littered with misunderstandings and broken promises, in which the British, the Russians, and later the Americans, constantly underestimated...