A good Samaritan was left needing 13 stitches to a cut on his face after he tried to break up a row between a man and a woman.
Brian Knight was at the Lee-on-the-Solent Community Centre when he stepped in to stop his friend, Simon Woodward, from beating up a woman.
Mr Knight stepped in as Woodward was fighting with the woman, who was his ex-girlfriend's sister.
But after Mr Knight intervened Woodward turned his rage on him.
The 37-year-old ran at his friend, calling him a traitor and headbutted him, knocking him backwards and cutting his face.
Mr Knight was taken to Queen Alexandra Hospital, in Cosham, where his wound was stitched up.
Representing himself at Portsmouth Crown Court, Woodward said he was sorry for what he had done.
And he told the court he was trying to turn his life around in the wake of the attack.
'I fully understand my actions were totally wrong,' he said.
'I know it doesn't excuse it but I was under quite a great deal of pressure at the time with access to my children.
'I have tried to turn my life around.
'I have sorted access to my children.
'I have even enrolled on a Learn Direct course to try and help me out academically.'
The court heard that Woodward, who has a previous conviction for assault, admitted what he had done after the police arrested him.
Woodward, of Compton Close, Lee-on-the-Solent, pleaded guilty to assault causing actual bodily harm.
He was given a 26-week prison sentence suspended for two years with 12 months of supervision from the probation service.
Judge Ian Pearson told him: 'What you did on this day I accept was out of character for you.
'There was a sudden loss of temper and you headbutted a man who was really acting as peacemaker.
'It was an unprovoked attack.
'You did use your head as a weapon.'
The judge ordered Woodward to pay 500 in compensation to Mr Knight.
'I hope Mr Woodward we don't see you again,' he said.
'I hope that you remain out of trouble.
'I'm confident that you will because you have been given an opportunity, as you say, to rebuild your life.
'I hope that you take it.'