Was the movie Gangs of New York based on true events?

The 2002 film Gangs of New York is based on Herbert Asbury's 1927 book of the same name. Asbury's book is a historical account of the real-life gangs that operated in New York City during the mid-19th century, particularly the conflicts between the Irish immigrants and the nativist Protestants. The film adaptation takes some creative liberties with the historical events, but it generally follows the broad outline of Asbury's book.

One of the most notable changes made for the film is the character of William "Bill the Butcher" Cutting, played by Daniel Day-Lewis. While Cutting was a real historical figure, he was not as prominent or influential as he is portrayed in the film. The character of Bill the Butcher was also given a more complex and sympathetic backstory than he had in the original book.

The film also simplifies some of the complex social and political issues that were at play during the mid-19th century. For example, the film does not go into much detail about the economic disparities between the Irish immigrants and the nativist Protestants, or the political corruption that was rampant at the time.

Despite these changes, Gangs of New York is still a relatively accurate portrayal of the real-life events that inspired it. The film does an excellent job of capturing the atmosphere of mid-19th century New York City, and it provides a glimpse into the lives of the men and women who lived in that time and place.