Two firefighters have been cleared of the manslaughter of four of their colleagues who died in a warehouse blaze in 2007.
Watch manager Adrian Ashley and station manager Timothy Woodward were acquitted of causing the deaths of Ian Reid, John Averis, Ashley Stephens and Darren Yates-Badley.
A third watch manager, Paul Simmons, was found not guilty earlier in the trial when the judge, Mr Justice Macduff directed the jury to acquit him.
Outside the court, Warwickshire Fire And Rescue Service chief fire officer Graeme Smith said: "I expected nothing less - it's crystal clear that [they] should never have been brought to court."
In a statement released after his acquittal Matt Wrack, general secretary of the Fire Brigades Union , said: "As a watch manager, Paul Simmons is a frontline firefighter.
"He is not and never has been a senior officer, let alone a fire chief as sometimes reported.
"The threat of prosecution has been hanging over Paul since November 2007 when four of his fellow firefighters died at Atherstone-on-Stour.
"Paul Simmons and his family are greatly relieved at the not guilty verdict."
Stafford Crown Court heard that Warwickshire Fire And Rescue Service responded to a call to a blaze at a vegetable packing plant.
Factory staff were evacuated and everyone was accounted for.
When firefighters arrived two teams of four firefighters were sent into the building to put the fire out, but one firefighter, Ian Reid, became "detached" from his three colleagues.
When he was located by a rescue team he was "disorientated" and "panicked".
It was "smoky" and he rushed from his would-be rescuers to try and find a way out.
Prosecuting, Richard Matthews QC said that over 90 minutes "successive" teams were sent in to try and locate Reid and the rest of his team but the operation was halted when the building became unstable. All four lost their lives.
The prosecution alleged that the managers "badly failed to fulfil their duties to the firefighters under their command" and their actions amounted to "gross negligence".
Richard Matthews QC argued that the four firefighters "lost their lives not in a valiant effort to rescue anyone but having been ordered into a smoke-filled large storage compartment containing mostly cardboard boxes, labels and some old furniture".
He said this was not a case of the "irritating trivialities of health and safety red tape" but the "needless loss" of four lives.
Mr Matthews had claimed the firefighters lost their lives when "no-one was in peril, no-one required rescue" and the situation should have been recognised as "obviously dangerous" and it had not been "properly assessed by those in command".
But an expert witness, Roger Day, told the court that the managers did not make a mistake by sending the firefighters into a burning building.
Warwickshire Police invested nearly £4.6m in "one of the most complicated investigations" ever undertaken by them. They received a Home Office grant of £3.45m.
Reacting to the not guilty verdicts, investigation officer Detective Superintendent Ken Lawrence said: "I promised we would do everything we could to determine how the four men... died, and to find some answers for their families and loved ones.
"I believe that we have done that.
"During the course of the investigation we discovered some safety critical issues which are of great importance for firefighters nationally and we shared those with the fire service for the benefit of all brigades."
He added: "We believe the deaths of Ashley, Darren, Ian and John were unnecessary.
"We do not want any more lives lost through the same kind of human misjudgement and organisational practices which have been uncovered.
"Those practices will, of course, be addressed in the basis of plea hearing for Warwickshire County Council, which has already pleaded guilty to a number of health and safety offences."
Mr Lawrence said the fire "may or may not have been started deliberately but our investigations have not resulted in anyone being prosecuted for that".
Following the announcement of charges against the three fire service managers, thousands signed an online petition demanding the withdrawal of them.
One signatory commented: "They had difficult decisions to make and no-one should condemn them unless they have been in the same situation".
Another read: "These men should never have been taken to court. They have suffered enough by the death of their colleagues".
