A teenager was sentenced to seven years in detention on Friday after a jury found him guilty of the manslaughter of Hailsham dad Darren Croxton.
The jury at Lewes Crown Court, found the youth, who cannot be named for legal reasons, not guilty of murder after deliberating the case since Tuesday.
An attempt to lift reporting restrictions to be able to identify the youth failed.
The jury also gave verdicts of not guilty to murder and the alternative charge of manslaughter for co-defendant Stuart Johnson, 19, of no fixed abode.
Mr Justice Singh said the youth had been in detention since January 2012 so would be out on licence in about two and a half years.
Mr Croxton, a father of two, died after a pre-arranged fight between two rival groups of people in a wooded area near the Diplocks estate in Hailsham on January 22 last year.
The court heard how a knife wound to his left thigh had severed a femoral artery, causing fatal haemorrhaging and cardiac arrest and Mr Croxton died the following day.