By the start of the 20th century, the gang had expanded beyond Corlear's Hook and changed its criminal focus from petty theft to pimping, using the many "disorderly houses" (brothels) along Allen Street to amass a small fortune.

According to Alfred Henry Lewis's 1912 book, The Apaches of New York, many of the gang members were also bicycle enthusiasts, likely owing to Eastman's own interest in the new riding machines.

However, as the gang war began to escalate, Tammany politicians forced the leaders to agree to a truce before losing control of the situation.

After Monk Eastman was arrested in 1904 for a street mugging, the gang threatened to disintegrate among warring factions, each trying to assert control.

However, possibly while attending a peace conference, Fitzpatrick was found shot to death at a local neighborhood saloon near Sheriff-Chrystie Street on November 1, 1904.

Paul Kelly arranged the murders of Zwerbach and Lewis, using an altercation with underling Louis "Louie the Lump" Pioggi to set them up for an ambush on May 14, 1908.

A failed attempt on Zelig's life at the hands of Julie Morrell resulted in the would-be assassin being killed in December 1911.

Both Sirocco and Tricker assumed control of what was left of the Eastmans after Zelig was killed by "Red" Phil Davidson shortly before he could testify against NYPD Lieutenant Charles Becker on October 5, 1912, in a trial for the murder of Herman Rosenthal.