Billed as a unique war art relic, the chunk of metal was brought back to Britain from Iraq by Nigel 'Spud' Ely after US Marines pulled down the statue of Saddam in April 2003.
Mr Ely, 52, who was working with a TV crew covering the fall of Baghdad, used a hammer and a crowbar to remove the buttock.
Now it is expected to raise thousands of pounds when it is auctioned off later this month to help injured ex-servicemen in Britain and the US.
Mr Ely said: "When we arrived in Firdos Square in the heart of Baghdad, the statue had just been toppled and the US Marines had erected a cordon of tanks to guard the square.
"But I wanted a piece of the statue – and when I mentioned to the marines that I was an old soldier and with the press they told me, 'No problem, buddy – help yourself'."
Mr Ely admitted: "I only wanted a piece big enough to put in my pocket, but I ended up with a chunk about 2ft square. I thought, 'What the hell am I going to do with this?'
"The real pain came when I flew back to London a few days later. I'd bought a large case from the local souk to put the bum in and had to pay a fortune in excess baggage. It's been with me all these years, but I decided it was time it did some good."
Hansons Auctioneers, which is handling the sale, expects global interest when the buttock goes under the hammer in Derby on October 27.
Auctioneer Charles Hanson said: "It should appeal to military and art collectors alike, not to mention anyone who has an interest in the major events that have helped shape the world we live in."Post published in: World News