Two soldiers were killed by "friendly fire" in Iraq because a senior Army officer failed to pass on vital information to his men, a coroner said.
The pair were killed in so-called "friendly fire"
An inquest is being held into the death of Cpl Stephen Allbutt, 35, of Staffs.
On Tuesday coroner Andrew Walker accused Lieutenant Colonel Lindsay MacDuff of causing the tragedy in 2003.
Lt Col MacDuff did not think he had to mention a change to the firing boundary between his group's patrol zone and another patch, the inquest has heard.
Remains 'not found'
Lt Col MacDuff is the commander of The Black Watch (BW), 3rd Battalion The Royal Regiment of Scotland, and the neighbouring patch, near Basra, was being monitored by the Royal Regiment of Fusiliers (RRF).
Andrew Walker, deputy assistant coroner for Oxfordshire, is hearing the inquest in Oxford into the death of Cpl Allbutt, a father-of-two from Stoke-on-Trent, in March 2003.
Trooper David Clarke, 19, of Littleworth, Staffordshire, died in the same incident when a BW tank near the Shatt al Basra Canal fired on a RRF tank.
But the remains of Mr Clarke were not found so no inquest can be held.
On Monday Lt Col MacDuff said although he did not communicate the change to the boundary, he did tell his men on the radio that two RRF tanks were near one of his tank troops.
But the radio log of the incident has since gone missing.
So far all soldiers and fellow officers giving evidence at the inquest have said they were not told about the RRF tanks.
Mark Percy, then operations officer for BW, responsible for conveying top-level orders to troops on the ground, was among them.
The coroner said to him: "This tragedy happened because this information was not passed to anyone in the Black Watch.
"I want to know why you did not know about it because you were the main conduit through which this information should have been passed."
The hearing was told that Lt Col MacDuff had been spoken to before the tragedy by Staff Sergeant Dave Hurst, liaison officer for RRF, when the commander of his Queen's Royal Lancers company, Major Richard Trant, expressed concern about battle group boundary information being confused.
Maj Trant said Sgt Hurst told Lt Col MacDuff about the presence of the two RRF tanks, both manned by men from the QRL, then attached to the RRF.
"Once he (Hurst) had spoken to him (MacDuff) I was fully confident they (BW) were aware where we were and we (RRF) were aware where they were," Maj Trant said.
Richard Hermer, a barrister representing the two dead men's families, asked: "If you were Major (he has since been promoted) McDuff being contacted by a liaison officer from a neighbouring battle group about two tanks near to you boundary, would you feel it necessary to impart that information to your troops?"
Maj Trant said yes, agreeing that "it was a mess" adding: "It clearly caused a lot of confusion."
The major said outside court: "We did our best."