The Defence Secretary has apologised to the families of British soldiers killed in Iraq while travelling in lightly armoured Snatch Land Rovers.
Sir Michael Fallon wrote to a number of families apologising for delays in bringing in alternative protected vehicles "which could have saved lives".
The sister of one solider who died said she cried when she received her letter from the Defence Secretary.
At least 37 UK soldiers died in conflicts in Iraq and Afghanistan while travelling in Snatch Land Rovers, with last year's Chilcot Inquiry heavily critical of delays in replacing them.
"I am fully aware of the struggle you have had to bring this matter to court over the last decade and I recognise this has had a significant impact on you and your family," Sir Michael wrote in his letter to the families.
"The Government entirely accepts the findings of Sir John Chilcot in the Iraq Inquiry in relation to Snatch Land Rover.
"I would like to express directly to you my deepest sympathies and apologise for the delay, resulting from the decisions taken at the time in bringing into service alternative protected vehicles which could have saved lives.
"I confirm that we have learnt lessons from this.
"The Government must and will ensure that our Armed Forces are always properly equipped and resourced."
The letter comes after a lengthy legal battle, which eventually saw the Supreme Court rule the families could bring compensation claims against the Government under legislation covering negligence and human rights.
Private Lee Ellis was killed in Iraq in February 2006, and his sister Karla Ellis said the explanation she received about his death "never made sense".
She told the Press Association: "I wasn't expecting much, a bit like the Iraq Inquiry with Sir John Chilcot, and I was just pleasantly surprised when I received it (the letter) – I think I actually cried.
"I just went wow, just like I did when I started to read the John Chilcot report.
"It's an amazing achievement. Our loved ones have not just gone down as a number, we've fought for their right to life and although obviously we can't bring them back, their legacy will hopefully go forward and give other people the courage to do the same thing."
Ms Ellis said the MoD had not followed through on a number of things after her brother's death, such as supplying her with information on the Land Rover, as well as making contradictory statements about the level of violence in the area on the day he died.
She added: "Obviously we're going to miss Lee forever so anyone, when you're grieving and trying to move on or rebuild your life around such a tragic incident, will find it difficult.
"You can either shut off from it or you can't, and I don't want to shut off from it so I think it's always going to be around."
Sue Smith's son, Private Phillip Hewett, was killed whilst driving a Snatch Land Rover in Iraq in July 2005.
Pte Hewett had told his mother he was driving a Warrior tracked armoured vehicle rather than the Snatch, so that she would not worry.
Prior to this, Pte Hewett had written to his uncle saying some soldiers had purposely lost their driving licences so they would not have to drive the Snatch.
Ms Smith criticised the MoD's conduct during her legal case, saying a lot of information it said was unavailable or too difficult to provide had already been handed over to Chilcot.
"Never for one minute did I think my family would be treated in this way," she said.
"I feel that the MoD have been dishonest in their dealings with me and have put me through a great deal of unnecessary stress in continuing to fight this case.
"I think they wanted to break me so that I would walk away but it only made me more determined to fight on."
The families' lawyer, Jocelyn Cockburn, has also received a letter from the Ministry of Defence confirming it had learnt lessons from Chilcot and was also procuring the next generation of armoured vehicles.
"This is an important victory for the Snatch Land Rover families, who have had to fight every step of the way to achieve justice," Ms Cockburn said.
"The Ministry of Defence's stance of 'delay, deny and defend' has caused untold suffering to already grief-stricken families over a needlessly long period.
"However, I am relieved that their battle is over and genuinely hope that their apology signals a sea-change in the way the MoD seeks to deal with bereaved service families."
General Sir Mike Jackson, Chief of the General Staff between 2003 and 2006, told BBC Radio 4's Today programme it was a fair assumption that a more heavily armoured vehicle would have offered much better protection for British troops.
He said he believed replacements for the Snatch Land Rover could have been brought in more quickly, adding: "The Army at that point did not have its own procurement budget.
"It does now, and perhaps that is one of the good lessons learned that's come out of this whole rather sorry story, we do have our own procurement budget now.
"Yes, better vehicles, better-protected vehicles were eventually procured, but the process was rather Byzantine and inevitably, thereby, lengthy."
An MoD spokeswoman said: "We offer our deepest sympathies and apologise for the delay in bringing into service alternative protected vehicles which could have saved lives.
"The Government acknowledges and fully accepts the findings of Sir John Chilcot's inquiry in relation to Snatch Land Rovers.
"Our Armed Forces now use a number of highly capable and extremely well protected patrol vehicles, including Mastiff, Ridgback, Husky and Wolfhound."