Irish gang wars
I don't follow the movies, so I don't know what this one is about. The chances are, though, that it is based on information taken from Herbert Asbury's The Gangs of New York, originally published about 1920. The book is "colorful", and doesn't cite sources, but nonetheless I have seen it cited in academic research from recent years. It's likely to be still in print, and otherwise should be easy to find.
The Irish were the bottom-rung immigrant group of the 1820s and after. One of my ancestors, Patrick Cassidy, was among them. Reports in NYC newspapers attribute most high-violence/low-profit crime to Irish perpetrators, as well as involvement in the drug subculture of the time -- the drug being alcohol. I have only a few references from the newspapers to the fact that many of these immigrants were Irish-speakers, but it seems that this was the case.
As for riots, the population of the city went from 120+ thousand in 1820 to 180+ in 1830 and continued to shoot up. The city was in no way ready to cope with this growth -- or inclined to try -- and the social tensions it caused led to violence between groups of the underclass: Irish against blacks, Irish against Germans, "Native Americans" against Irish, Catholic Irish against Protestant. A riot arose out of a parade of Protestant Irish to celebrate the anniversary of the Battle of the Boyne in the mid 1820s. There were also brawls between Irish groups known as the "Corkonians" and the "Far Downs". The recent book about the Five Points says that the Earl of Cork was very active in promoting immigration of his tenants to America. The Far Downs were evidently from Co. Down, and I assume that they were Protestants, but maybe this was just a regional squabble between Catholic gangs.
One of the post-famine gangs prominent in Asbury's book is the "Dead Rabbits". I have an early reference to them describing them as a gang of boys. Evidently, like some recent NYC gangs, what started as a gang of teenagers maintained its unity afterits original members were adults.
George A. Thompson
Bobst Library, New York University
Author of A Documentary History of "The African Theatre", Northwestern Univ. Pr., 1998.