Sergeant Steve Roberts, from Shipley, West Yorkshire, was killed by so-called friendly fire on March 24 2003.
The 33-year-old, a commander in the Royal Tank Regiment, died when he was attacked by a stone-wielding Iraqi man while manning a checkpoint outside the southern city of Az Zubayr.
An Army Board of Inquiry found the Browning pistol he used to try to shoot his attacker failed and he was shot by a comrade in a Challenger tank who was trying to protect him but was not trained to know his high-powered machine gun was inaccurate at short range.
The inquest into Sgt Roberts’s death heard he was left exposed by “serious failings” in the Army’s supply and training methods which meant he had to give up his personal body armour just three days before.
His widow, Samantha Roberts, has campaigned for better equipment for UK forces since her husband’s death.
Her lawyer, Geraldine McCool, said Sir John’s report highlights much of what was already feared about the body armour shortages.
Ms McCool said: “It’s absolutely crucial that lessons are learned from this inquiry in order to protect our soldiers in any current and future conflicts. For our troops and their families it is a matter of life and death.
“Whatever the reasons for going to war, there is simply no excuse for sending our troops into Iraq, or any other war zone, without providing them with the most appropriate equipment and training to help prepare them for battle.
“The inquest and investigations into Sgt Roberts’s death proved that he - along with thousands of others - was not given Enhanced Combat Body Armour which would have saved his life. The descriptions of tracking where body armour was and who was in possession of the available sets paints a picture of chaos where no-one really knew what the situation was on the front line.”
Ms McCool, who is head of the military injuries team at Irwin Mitchell, said: “David Cameron has today accepted that sending troops into battle without the right equipment was unacceptable and it is crucial Government never forgets the consequences.”
She said that now all personnel deployed on operations must have a full set of Enhanced Combat Body Armour which is what Sgt Roberts’s family has campaigned for.