A former Royal Marine ruined a niece’s 18th birthday party when he beat up the teen’s stepfather after drinking ’10 to 15’ Jägerbombs and eight beers in an hour.

Phillip Cooper, 35, was said to have demanded of his brother-in-law ‘if you want some come and f***ing get some’, after the man challenged him about an altercation between him and two other women on November 5 last year.

Ignoring attempts by others to defuse the situation, Warwickshire man Cooper knocked his victim to the ground and then set about him with his boots, repeatedly kicking him to the head.

The victim – a former soldier whose PTSD from his time in the Army was triggered by the attack – was left with two black eyes and a footprint-shaped bruise to the side of his neck.

He was off work for a week, his sleep was disturbed and it took ‘a few weeks’ to recover fully from his injuries.

Cooper was said to have launched the attack after, over an hour, drinking two pints of Fosters lager, six 'large' bottles of Estrella beer and '10 to 15' Jägerbombs - equivalent to more than 40 units of alcohol or three times the recommended weekly intake of booze. 

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The 18th birthday party, which had cost around £1,000 to put on, finished early. Managers of the Royal British Legion hall in Littlemore where the event was being held kicked the partygoers out after the police turned up to deal with the fighting.

Jailing him for 11 months, Recorder John Bate-Williams said: “At premises where the courage and valour of servicemen and women are commemorated, you brought disgrace to the name of your claimed regiment, the Royal Marines.”

He branded the attack ‘drunken and cowardly’, taking place 10 years after he was discharged from the Marines.

“This was an event which should have been an 18th birthday celebration,” the judge said, adding: “It was very chilling to see the way you put the boot in – literally.”

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Cooper, of Lighthorne Heath, near Leamington Spa, pleaded guilty at the magistrates’ court to a single offence of causing actual bodily harm.

The defendant had a history of violence, the court was told, with 11 previous convictions for more than 20 offences. They included five offences of violence in the past eight years.

In one incident, he was said to have battered a man over the head with a computer keyboard.

And he appeared before the crown court on Thursday from Cardiff Prison, where he was serving a short jail sentence for drink driving.

Mitigating, Emma Richards said her client recognised that drinking was a problem for him and he was getting help while in custody.

Cooper was ordered to pay £300 in compensation.