Mourner Adam Main, 35, of Morris Crescent, Boldon Colliery, struck his victim so hard he collapsed unconscious on the floor of the Beggar’s Bridge in East Boldon.
The 11pm attack on Friday, November 29, left his 18-year-old victim with memory loss condition retrograde amnesia and a lip that had to be glued by medics.
In an impact statement read to magistrates in South Tyneside, the teenager said he now feared returning to a job he had previously felt safe doing.
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Main, who left the Army in 2006 after five years of service which had included tours of Iraq, has been spared jail but handed a suspended sentence.
Magistrates told him they could not understand how someone of his previous professional standing – and being a dad-of-two – could have committed such an attack.
Prosecutor Kirstie Devine said: “The victim is a glass collector at the Beggar’s Bridge pub.
“The defendant was part of a funeral party and had earlier been described as being hyper.
“(The victim) walked past the defendant to collect glasses and the defendant threw a punch.
“It contacted with (the victim’s) face, hitting his glasses, and he has fallen to the floor.
“He doesn’t remember the incident, but he does recall coming around on the floor and being helped by a woman.
“He suffered retrograde amnesia and had to have his lip glued.”
She added: “The aggravating factors are that this was a person working in a pub, the defendant was intoxicated and the ongoing issues to the victim.”
In his statement, the victim said: “I’m concerned about working now.
“I always thought that I was safe, but I’m not sure how I feel now. I’m concerned about going back.”
Michelle Stonley, defending, said Main had recently been diagnosed with Post Traumatic Stress Disorder as a result of his Army career and had just completed treatment.
She said: “He has no recollection of this incident. He had drunk too much alcohol while attending his best friend’s mother’s wake.
“It’s one punch. Mr Main was not being violent or aggressive beforehand.
“He started to drink a lot more when he left the Army. He had taken part in a number of tours of Iraq.
“He then started to increase his drinking to help him cope with the horrors he saw.
“This has been a wake-up call. He’s given up alcohol.”
John Lee, chairman of the bench, told Main: “It’s hard to fathom why someone of your circumstances and background, and married with two children, could do such a thing.
“It’s a particularly upsetting and violent incident.
“We take the fact that you threw a punch and knocked him out and knocked him to the floor, as being akin to using a weapon.”
Main was given a four-week jail sentence, suspended for 12 months, and 20 days of rehabilitation work with the Probation Service.
He must pay the victim £150 compensation and there was a £122 victim surcharge.