Jonathan Powell, Tony Blair's aide during his time in office, told the Chilcot Inquiry into the Iraq war that Blair's assumption that Saddam Hussein had WMD was (in the cruel light of reality) wrong.
Blair went to war based on a long-standing "assumption" that Saddam Hussein still possessed weapons of mass destruction, because he had used them in the past.
Blair was once described at school as being lazy when it came to details. True to form when deciding to go to war, rather than use up to date detailed intelligence, he based is decision on past assumptions.
Powell told the inquiry that intelligence on Saddam's WMD was not the pivotal factor in the decision to go to war in Iraq.
Powell is quoted in the Telegraph telling the inquiry:
"Iraq didn't have weapons of mass destruction. We were wrong. The intelligence was wrong.
When our forces went in, we were absolutely amazed to discover there weren't any weapons of mass destruction."
When asked if he had any concerns about the intelligence not being up to date, Powell said:
"We had an assumption, and we had that assumption because Saddam Hussein had lied about using WMD and he had lied about getting rid of them. We had bombed Iraq in 1998 on that basis and it would have taken some quite strong evidence to suggest he had got rid of them.
We didn't really have any doubts about it and I don't think other people had any doubts about it."
Beware leaders who rush to war without doubts, they will lead themselves and their people to destruction.