A drunk went into a pub armed with a carving knife before punching a customer in the face and knocking out his tooth.
Daniel Gallagher was jailed for 18 months over the disturbance at the Old Red Lion, Whinmoor, Leeds.
Leeds Crown Court heard how the 56-year-old grandfather behaved like a 'Jekyll and Hyde character' due to his heavy drinking.
Danielle Gilmour, prosecuting, said Gallagher was clearly drunk when he tried to get served at the bar at 4.30pm on February 27 this year.
Gallagher became aggressive when a member off staff refused to serve him.
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The prosecutor said the defendant then "invited everyone outside to sort it out."
A customer at the bar became concerned when he saw a black handle sticking out of Gallagher's trousers.
The customer pulled at the handle to find it was a ten-inch carving knife.
He took hold of the weapon and threw it behind the bar out of Gallagher's reach.
The defendant continued to be aggressive and punched the customer as he tried to escort him off the premises.
Miss Gilmour said the man lost a tooth in the attack.
A witness described Gallagher's behaviour as "crazy and dangerous."
Other customers managed to get Gallagher out of the pub.
Police were contacted and he was arrested later that evening.
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Gallagher, of Pogsons Cottages, Whinmoor, pleaded guilty to common assault and possession of a knife in public.
He has previous convictions for assault and drink driving.
Stuart Field, mitigating, said the former mechanic had only started to commit offences in recent years after losing his business and the breakdown of his marriage.
He said: "He is a Jekyll and Hyde character because he is quiet, unassuming and polite - a perfect gentleman and a pleasure to deal with.
"But when the drink took over this is what happened on this occasion."
Jailing Gallagher, Judge Tom Bayliss, QC, said: "This created a risk of a serious disturbance.
"Mr Gallagher, you are a heavy drinker and it has cost you dearly.
"It has cost you your business, it has cost you your marriage and now, I'm afraid for the first time in your life, it is going to cost you your liberty.
"The courts must do what they can to deter people from carrying knives.
"Those like you who go into public houses carrying knives must expect to go to prison."