Fresh from being officially applauded as Ireland’s biggest box office star of all time, actor Liam Neeson popped into famous Irish-American New-York bar The Dead Rabbit this week with a special present for its Belfast owners.

Inspired by the spirit of the Dead Rabbits, an Irish-Catholic gang in downtown Manhattan who fought it out with the nativist Bowery Boys gang in 1850s New York, the Dead Rabbit Grog and Grocery mixes the best of an Irish pub with the traditions of Old New York and Irish America. Now they can add another incredible piece of memorabilia to their perfectly-crafted atmosphere.

Neeson, who played the fictional leader of the Dead Rabbits, Priest Vallon, in the 2002 film “Gangs of New York,” popped into the Financial District bar to gift the award-winning cocktail-makers with the massive Celtic Cross that Neeson's character sports in the opening scene of the movie and which was used as a weapon in later scenes.

Posting a picture of the actor and the cross on Facebook, the bar’s owners Jack McGarry and Sean Muldoon wrote, "Remember the big Celtic cross that Liam Neeson carried with him in Gangs of New York?

"Well the coolest thing happened last night..."

Read more: Liam Neeson is the biggest Irish box office star of all time

Muldoon told the Belfast Telegraph: "The gift he presented us with is the actual battle cross that he holds in the opening scene in the film 'The Gangs of New York.'

"Liam starred as the Dead Rabbit gang leader in that film. He said he had to beg Martin Scorsese for it (the cross,) and Martin only agreed to give him it because the sword inside it was broken. I asked him how it got broken, and he said, 'I broke it over some Nativist's back.'

"We asked him if we could take the picture and post it on our Facebook page for our fans back home, and he totally obliged. So this is for them. We will keep it in a glass display case and will hang it proudly in our parlor bar.

"It – together with an autograph of John Morrissey, the actual Dead Rabbit gang leader – dated 1861, are the two dearest possessions we own."

While the character of Priest Vallon is fictional, the true leader of the Dead Rabbits was a man named John Morrissey, a Tipperary-born bare-knuckle fighter who would make his name in the ring before turning to politics and dying an extremely rich man.

Morrissey immigrated to New York when he was young. He was often known as “Big Smoke,” and he faced off with his rival William Poole, the real "Bill The Butcher," played by Daniel Day-Lewis in the movie, not because he wanted revenge for the death of his father but because he and his gang were working on behalf of Tammany Hall to prevent Poole from seizing ballot boxes and rigging an election.

Despite the violence on New York's streets at the time, Big Smoke and Bill the Butcher did not meet each other in gory battle as Hollywood would lead us to believe. Instead, the two bare-knuckle fighters faced off in the ring, where it’s said Morrissey lost. A friend of Morrissey's would have his revenge, however, when he shot and fatally wounded Poole a few weeks later.

Despite retiring from fighting, Morrissey continued to look after the interests of the Irish in the US as a Congressman, serving two terms from 1867 until 1871.

The Dead Rabbit opened in 2013 and has won countless awards in its short history, including the World’s Best Bar in 2015. The bar can be found on Water Street in lower Manhattan.

Read more: In Focus - Sean Muldoon: Belfast native and owner and manager of Dead Rabbit Grocery and Grog in Manhattan

New York Irish bar is presented with an incredible part of movie-history memorabilia.Dead Rabbit / Facebook