The collapse of the George W. Bush-era Republican Party is a multifaceted story, but no chapter stands out as clearly as the war in Iraq. As the occupation has dragged on and the U.S. casualties have mounted, Bush has watched his public approval ratings spiral downward. By the time the contested GOP primaries came around, even a healthy proportion of Republican voters were saying that they strongly or somewhat disapproved of the war in Iraq. Under the circumstances, it's not surprising that the GOP is poised to nominate a presidential candidate who will appeal to its anti-war base. What is...