Four of the Haymarket affair defendants were executed. August Spies, Albert Parsons, Adolph Fischer, and George Engel were hanged in Chicago on November 11, 1887.
The case grew out of a May 4, 1886, labor rally at Haymarket Square, where an unknown person threw a dynamite bomb at police attempting to disperse the meeting. Eight anarchists were prosecuted for conspiracy, although the prosecution did not establish which defendant threw the bomb, and only two of the eight were present at the rally when it exploded.
Seven defendants were initially sentenced to death. Governor Richard Oglesby commuted the sentences of Samuel Fielden and Michael Schwab to life imprisonment, while Louis Lingg died by suicide in jail before the scheduled executions. The remaining four were therefore hanged. Oscar Neebe received a 15-year prison sentence and was not executed. Governor John Peter Altgeld later pardoned Fielden, Schwab, and Neebe in 1893, criticizing the trial.