A British court on Tuesday cut a soldier's sentence for killing an injured Taliban fighter to seven years after his murder conviction was reduced to manslaughter on the grounds of diminished responsibility.
Veterans hugged, cheered and waved flags bearing former Royal Marine Alexander Blackman's image outside the Royal Courts of Justice in London after the ruling, which means he could be released within weeks.
Blackman was sentenced in 2013 for shooting the fighter at close range in Afghanistan's Helmand Province on September 15, 2011, after the man was seriously injured by fire from an Apache helicopter.
"There you are. Shuffle off this mortal coil... It's nothing you wouldn't do to us," Blackman was heard saying, paraphrasing William Shakespeare's "Hamlet", in footage captured by a camera on another soldier's helmet.
"Obviously this doesn't go anywhere, fellas. I just broke the Geneva Convention," he said to his fellow Royal Marines, a reference to international laws governing the treatment of prisoners of war.
Blackman was originally sentenced to life in prison with a 10-year minimum although this was later reduced to eight years to account for the fact he was suffering from combat stress disorder.
That was the same reason given by judges earlier this month for downgrading his conviction to manslaughter.
"As with any person sentenced to a determinate term, his release will ordinarily be at the half-way point of the sentence," judge Robert Thomas said on Tuesday.
That means Blackman would be released three and a half years after his original December 2013 conviction.
Apart from army veterans, the campaign to free Blackman also had the support of the Daily Mail newspaper and best-selling author Frederick Forsyth.
The case marked the first time since World War II that a British soldier was convicted of a murder carried out on the battlefield.
"You treated that Afghan man with contempt and murdered him in cold blood," judge Jeff Blackett told Blackman at his court-martial in 2013.
"By doing so you have betrayed your corps and all British service personnel who have served in Afghanistan, and you have tarnished their reputation," Blackett said.
The conviction was supported by Britain's chief of the defence staff at the time, Nicholas Houghton, who said: "Murder is murder, this is a heinous crime."
But earlier this month, judges said Blackman was suffering from a "combination of stressors" that impaired his ability to make rational decisions.
They said it was "clear that a consequence was that he had developed a hatred for the Taliban and a desire for revenge".