Knowing in 2003 what I know now, I would not have backed the UK involvement in Iraq.
It is clear that the invasion itself was massively mishandled and could have been put back at least a year.
That said, Tony Blair and George W Bush, the former of which appears to have had good intentions, are not solely responsible for the chaos in Iraq.
Saddam himself created a toxic cauldron of sectarian hatred that the Coalition opened. Iraqis who should have been working together to make a better country engaged in corruption and score settling instead. Terrorists decided to attack civilians instead of actual troops.
There was no conspiracy (I could have done a better job at organising it) but instead a massive chain of failure by many people.
And the innocent, as always, suffered for it.
Pray for your leaders that they do not make more mistakes like this.