Arguments had been raging in the minutes leading up to the ‘brawl’ in the Royal Standard pub, kicked off when Robbie Deacon launched a series of attacks.
One man, Steven Payne, was left with a piece of bone displaced in his skull and a broken collar bone after the attack.
Deacon, 25, was in the city pub, in Edinburgh Road, at a barmaid’s leaving do in the early hours of January 15.
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CCTV played at Portsmouth Crown Court showed how his partner’s mother was being ejected from the pub when he came in and he started ‘throwing punches’.
He was quickly bundled out but then punched a female member of pub staff. Mr Payne then intervened.
Prosecutor Daniel Sawyer told the court Mr Payne ‘walks backwards and the defendant steps forward, punching Mr Payne, knocking him to the ground.
‘He lands on the ground unconscious; and as the defendant walks past, (Deacon) stamps on his head.’
The judge gasped ‘oh god’ as the CCTV was played, showing how Deacon punched Mr Wright again as he fell back.
Deacon walked back into the pub after the brutal attack and assaulted more people.
Mr Sawyer said things had been ‘calming down’ but others were still fighting.
During the melee Deacon grabbed and bent over another man, Simon Wright, repeatedly hitting and kneeing him.
Others he attacked were:
n Elliot Tribbeck and Jack Woods who tried to separate two women fighting. One man suffered a broken nose and the other was knocked out.
n Adam Silverthorne, who was punched in the jaw.
n Laura Bridgeford, who he punched outside the pub.
n Kim Jones, attacked at the same time as Mr Wright.
Before jailing Deacon, judge Howard Palmer QC said: ‘Any one of those assaults could have ended up with one of those people hitting the floor and ultimately dying from being knocked out with a single blow.
‘Mr Payne was certainly knocked to the floor with a single blow and as a result lost consciousness, and suffered a significant period of retrograde amnesia.
‘That could have happened to any of the other six victims in this episode.’
Rebecca Austin, mitigating, said: ‘It started as an argument between women which involved his partner and no doubt, under the influence of drink my client reacted in a way that was wholly and utterly inappropriate.’
Deacon, of Furze Lane, Milton, pleaded guilty to causing grievous bodily harm with intent, causing actual bodily harm and five charges of assault by beating.