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Kenneth Branagh is Colonel Tim Collins
Colonel Tim Collins' eve of battle speech to the Royal Irish Regiment has become an iconic moment of the Iraq War. Reporter Sarah Oliver was there to scribble down his words as he spoke.
It is known now as "that speech".
At the time it was nothing more than housekeeping. Keep taking your anti-nerve agents, don't go anywhere without your gas mask and morphine and no, you haven't got the only bullet proof sleeping bag in Kuwait so get up, get ready, we're going to war.
But as Colonel Tim Collins told his men: "We go to liberate not to conquer, if you are ferocious in battle be magnanimous in victory" his oratory grew into something else entirely.
It became the rallying cry of a veteran commander about to lead 1,000 young soldiers into the breach.
It was a reminder to be both brave and merciful, not to let military purpose diminish respect for civilian life.
It brought to them, as it did me, a clarity of vision which had not existed before.
The merry, dusty life of camp Fort Blair Mayne was to be packed away.
Iraq and its unknowable terrors lay ahead. Just as it was too late for the White House and Downing Street to pull back from the brink, it was too late for any of us on that border to turn for home.
I struggled to judge the impact of his words on the wider world. In the desert, in the dying moments of a day-long sandstorm and just hours from invasion, they had made the tectonic plates shift under my boots.
I was unsure how they would play in the comfort and safety of London's media village.
It was the following day before their force became clear.
I was in a trench asleep under a camouflage net when my phone began to ring.
"That bloke you're with, the cigar and sunglasses colonel," said a friend. "He's just gone box office."
And then the klaxon which signifies a gas attack started to wail.
Pure, white, fumbling terror, not a training session, actual incoming, nine seconds to secure your gas mask with the prospect of firing a spring loaded syringe of atropine (nerve agent antidote) into your leg and breaking your own thigh bone if you don't. It was the first of many alerts that day.
And so I left behind all thought of the speech and dealt with a new and very different reality.
Up to that point I'd only planned going to war, I hadn't dwelled on what the other side might actually do when I got there.
I wasn't na´ve; I'd been in war zones around the world, but never before as an embed at the heart of a military machine.
The day which unfurled after that dramatic dawn was extraordinary. I was with 16 Air Assault Brigade - 5,000 fighting men and all their armour.
It was like being on the inside of every war film you've ever watched and thought "it can't possibly look like that".... Only it does, it really does.
Because some parts of war haven't changed in a century. The bit where you stop in a barren desert, dig a hole and then just live in it, for example.
In the film Oliver is portrayed as scribbling down the speech
It was in my trench (which I'd dug myself because the Army doesn't take passengers) that I felt the disconnect from my ordinary life.
It receded like daylight when you faint, suddenly and completely. I think it has to or you wouldn't go.
It was dark when we eventually crossed the border into the burning oilfields of Ramallah. Great infernos blazed from wellheads creating a hellish landscape.
The silver light cast by the moon bleached the grey sand to the colour of bones and I wondered if I might leave mine there.
American troops had carved the path a few hours earlier. They'd left a ragged sign. It said: "Welcome to Iraq".
Sarah Oliver is a journalist for the Mail on Sunday.
Kenneth Branagh is Colonel Tim Collins in Ten Days to War on BBC Two at 2230GMT, Wed 19 March.