What was actually achieved by the Invasion and Occupation of Iraq?

As the Brits totally withdraw from the hell that is Iraq, over 250 deaths in 3 days by suicide bombers in the Capital Baghdad let alone the out-lying villages, 6 000 dead Americans, 1 million dead Iraqis, 11 million displaced people and a security and economic meltdown... I have to ask what was achieved by Bush's murderous folly?