The police were aware of the meeting and feared another outbreak of violence. Chicago mayor Carter Harrison planned to attend the meeting himself and warned police not to interfere unless necessary. At the demonstration, the mayor reported to Police Captain John Bonfield “that nothing had occurred yet, or looked likely to occur to require interference,” a conclusion the captain shared, although he wished to retain a few men in case the situation changed. When Bonfield's detectives reported the speakers were threatening the government, the police marched to the square.
 Paul Avrich, The Haymarket Tragedy, (Princeton: Princeton University Press, 1984), 191-3.
Douglas O. Linder Famous Trials Courtesy of Chicago Historical Societyhttp://www.law.umkc.edu/faculty/projects/ftrials/haymarket/attention.html
 Illinois vs. August Spies et al., Vol L, 32-33 (Ill 1886). Haymarket Affair Digital Collection, http://www.chicagohistory.org/hadc/transcript/volumel/000-050/L026-052.htm