The disturbance at HMP Doncaster's Young Offenders' Institute broke outÂ between two inmatesÂ at around 3.30pm on April 17 this year, before several others became involved, Sheffield Crown Court heard.
'The incident has been described by as officers as chaosÂ and mayhem. Prisoners knocked a pool table onto its side, and are described as being completely out of control,' said Olivia Murray, prosecuting.Â
Ms Murray described how after initially hiding, defendant, Billy Cameron, emerged from the prison bathroom carrying a plastic chair.Â
She said: 'He was seen to walk over to the railings, and throw the chair over the landing. It hit the complainant on the head. It caused pain and bleeding, and a two-inch cut that had to be glued.
'One of the officers spoke to the defendant, and he said he didn't intend to hurt anyone and just got caught up in the incident.'
The court heard how Cameron, 19, subsequently told the police that he threw the chair in a bid to try and defend himself from pool balls that were being thrown by prisoners.Â
Through a victim personal statement read out in court, the complainant said the incident had given his family cause for concern and had made him consider whether he should leaveÂ his job.Â
'Following the incident I had to force myself to go back to work, and to go back to the wing and overcome my fears,' he said.Â
Cameron, who was serving a 48-monthÂ prison sentence for a number of offences -Â some of which involvedÂ the use of violence - at the time of the incident, pleaded guilty to a charge of assault occasioning actual bodily harm at an earlier hearing.Â
In mitigation, Helen Chapman told the court that Cameron, of HMP Doncaster,Â was taken into care as a child, and began getting into trouble after he found himself back in care at the age of 15Â when a six year foster placement ended.Â
'It was this defendant who requested an audience with the complainant the day after the incident, and gave what the prison officer considered to be a genuine apology,' she said.Â
The judge, Recorder Darren Preston, sentenced Cameron to an additional eight months in prison.
He said: 'I accept that you were initially hiding in the bathroom, and you came out wielding a chair to defend yourself from flying pool balls, but you went beyond self-defence when you recklessly threw the chair over the landing.'