One of the most successful waterfront gangs of the mid-late 19th century, the "Swamp Angels" dominated the dockyards, of New York Harbor, from the 1850s into the post-Civil War era. The headquarters of the gang, was a rookery, known as "Gotham Court", on Cherry Street, in Lower Manhattan, which gave them access to the sewers, under Cherry Street, which allowed the gang to easily raid the East River dockyards and sell off its valuable cargo, within hours, before the thefts were discovered, the following morning. With the Swamp Angels' success, the New York City Police Department began posting snipers, to guard the waterfront. However, when these law enforcement measures did not slow down the Swamp Angels' criminal activities, the police were forced to send, teams of, officers, into the sewers, which resulted in regular battles, between the police and the gang members. Eventually, regular, police patrols, of the sewers forced the gang to halt its use, of the underground labyrinth although, the gang continued to hijack cargo ships as they were being unloaded onto the wharfs. The Swamp Angels were less visible, after 1860, but continued to operate, on the waterfront, according to one source, until eventually they merged, with the rival waterfront gangs, into the White Hand Gang, at the end of the 19th century.