The war in Iraq began with an impressive array of precision and determination by the United States and its allies. But since the fall of Baghdad, Americans have learned the pretext for war was fallacious. The United States now finds itself in an increasingly unpopular war that costs billions of taxpayer dollars and thousands of lives. Yet no one has articulated a clear design for winning the war. Now that America is engaged, it cannot withdraw. But neither can it fight indefinitely. Throughout history, no invading army has ever held on to a possession taken by force. Even though Greece and...