Daniel Day-Lewis’ character Bill the Butcher is based upon New York gang leader Bill Poole.
A famed pugilist and gang leader, Poole died from a gunshot wound to the leg; the result of a well-known public feud with John Morrissey, an Irish immigrant, and enforcer for New York political organization Tammany Hall
To recreate Bill the Butcher’s fake eye, Daniel Day-Lewis had his eyeball coated with prosthetic glass. Ever the committed thespian, Day-Lewis then taught himself not to blink while tapping the ‘fake eye’ with a knife’s blade.
While filming a fight scene, Leonardo DiCaprio accidentally broke Daniel Day-Lewis’ nose. Naturally. Day-Lewis simply continued with the scene.
The naming of The Priest’s gang as ‘The Dead Rabbits’ is actually a period-specific play on words. The word ‘Rabbit’ is a phonetic corruption of the Gaelic word ráibéad, meaning ‘man to be feared’. Dead is a slang term from 1850’s New York meaning ‘very’. Therefore a man who is a Dead Ráibéad is a man who is to be greatly feared.
via Wikimedia/ Mika
According to an interview with Rolling Stone, Daniel Day-Lewis listened to a lot of Eminem to prepare him for the role of Bill the Butcher.