Excellent Economist article on why the war in Iraq failed:
What went wrong? The most popular answer of the American neoconservatives who argued loudest for the war is that it was a good idea badly executed. Kenneth Adelman, he of the “cakewalk”, has since called the Bush national-security team “among the most incompetent” of the post-war era. Others also blame the Iraqis for their inability to accept America’s gift of freedom. “We have given the Iraqis a republic and they do not appear able to keep it,” lamented Charles Krauthammer, a columnist for the Washington Post.
That excuse is too convenient by half: it is what the apologists for communism said too. But there can be no denying that the project was bungled from the start. Western intelligence failed to discover that Saddam had destroyed all his weapons of mass destruction (WMD), the removal of which was the main rationale for the war. However, the incompetence went beyond this. The war was launched by a divided administration that had no settled notion of how to run Iraq after the conquest. The general who warned Congress that stabilising the country would require several hundred thousand troops was sacked for his prescience.
Mr Rumsfeld’s one big idea seemed to be that it was not the job of the armed forces he was “transforming” to become policemen, social workers or nation- builders. As a result, he sent too few and they did nothing to prevent looters from picking clean all Iraq’s public buildings the moment the regime collapsed. “Stuff happens,” was the defence secretary’s comment, a phrase used later as the title of an anti-war play in London’s West End.