Ive, you're going to compare Hitler and Galtieri, both of whom attacked British territory, with Saddam, who doesn't even control the northern and southern parts of his own country?
Hitler didn't attack British territory to provoke the Second World War. He attacked Poland.
The point is, that many naysayers in the British government and the peace movements of the time said many of the same things - "war is unpredictable" and so on. Well that's true. Well done. But that doesn't mean that wars should not be fought, nor that there aren't legitimate reasons to fight.
Saddam Hussein has invaded two of his neighbours in the past, is obviously hiding WMD, trying to obtain WMD, funds terrorism. He is a nasty piece of work who should be taken out. And it is clear that just hitting him with a few cruise missiles will not do the job.
Yes going in is unpredictable. Going anywhere is unpredictable. Which makes your perfect prescience that it will all turn out badly all the more curious.
Regards, Ivan