A drunk left a Good Samaritan with a broken jaw after mistaking him for a robber when he tried to help a woman in distress during a night out in Leeds.
Christopher Wheatley, 29, punched the victim out cold with a single blow which also left him with fractured ribs.
Leeds Crown Court heard the 56-year-old victim had been enjoying a night out with his partner in Leeds city centre in the early hours of June 9 this year.
Paul Canfield, prosecuting, said the couple were on their way back to their hotel when they saw a young woman walking towards them near Briggate.
Mr Canfield said the woman appeared cold and they were concerned about her walking alone through the city centre.
The victim suggested to his partner they try to help her.
His partner walked over to the woman to ask if she was alright.
Mr Canfield said Wheatley had been walking behind the couple and had no association with the young woman but suddenly became aggressive.
He said: "He was angry and shouting at him 'get the 'f*** away from her and leave her alone.'"
The victim tried to explain that he was helping the woman but was punched in the face by Wheatley.
He fell to the ground and was knocked unconscious by the blow.
The defendant then pointed his finger at the victim's partner and told her to get away.
Wheatley was then seen striking up a conversation with the woman.
He handed himself into police after recognising himself in a media appeal to trace the attacker.
Wheatley admitted in interview that he was drunk and had seen two people taking a girl's bag earlier in the evening.
He told officers he felt "sick to the stomach" when he was shown CCTV footage of the assault.
Mr Canfield said the victim still had trouble eating four months after the incident.
He needed an operation to have a plate and screws fitted to his jaw.
Wheatley, of Arthington Grove, Hunslet, pleaded guilty to inflicting grievous bodily harm.
Probation officer Helen Nunns said Wheatley said in interview that he thought the woman was being mugged.
She said: "When police gave him the information he was devastated and shocked about what happened to the victim.
"He said he doesn't really remember a lot from that night."
The court heard Wheatley worked as a scaffolder and has a good work record.
Wheatley was ordered to pay £2,000 compensation to the victim and do 100 hours of unpaid work.
Judge Tom Bayliss, QC, said: "You misunderstood their actions and you acted aggressively towards that man."