May Day was coming up and the feds were worried. In April 2015, the FBI and Department of Homeland Security sent out a bulletin warning that "anarchist extremists will probably engage in criminal or violent activity in one or more US cities on 1 May 2015 and may attempt to co-opt legal protest activity to carry out attacks."
It was the anniversary of the deadly 1886 labor unrest in Chicago's Haymarket. Several anarchists were executed for the violence back then, and in the 2015 bulletin's words, May 1 became "an international day honoring workers' rights that frequently results in anarchist extremist violence both domestically and internationally." To emphasize that anarchism was still a live threat, the Feds listed several recent anarchist attacks in their bulletin.
