Haymarket Affair Bombing and Police Violence Trigger Massive Anti-Labor Backlash

A peaceful labor rally at Haymarket Square in Chicago advocating for the eight-hour workday descends into violence when an unknown person throws a dynamite bomb at police officers attempting to disperse the gathering. The blast and ensuing retaliatory police gunfire kill seven police officers and at least four civilians, with dozens more wounded. The bombing occurs on the second day of protests responding to police brutality on May 3, when police killed one person and injured several others while protecting strikebreakers at the McCormick Harvesting Machine Company during a national eight-hour workday campaign organized by the Federation of Organized Trades and Labor Unions.

Chicago Mayor Carter Harrison attends the May 4 rally and pronounces it peaceful before departing. After Harrison leaves and most demonstrators depart, a contingent of 176 police officers arrives at 10:20 PM and demands the remaining crowd disperse. An unidentified individual—whose identity remains unknown to this day—throws a homemade bomb into the police formation, triggering the explosion and subsequent police gunfire that causes most casualties. Despite no evidence linking them to the bombing, eight men labeled as anarchists are arrested and convicted in a sensational trial where the jury is considered biased and no solid evidence connects the defendants to the bombing. Judge Joseph E. Gary imposes death sentences on seven men, with the eighth sentenced to 15 years in prison.

Four men are hanged on November 11, 1887; one commits suicide on the eve of execution; and Illinois Governor Richard J. Oglesby commutes two death sentences to life imprisonment in response to widespread public questioning of their guilt. Governor John P. Altgeld pardons the three surviving activists in 1893, declaring the trial one of the nation’s greatest miscarriages of justice. The Haymarket Affair triggers catastrophic consequences for organized labor: Knights of Labor membership plunges from over 700,000 to under 100,000 within a year due to false rumors linking the organization to anarchism and terrorism, despite only two of the eight defendants being Knights members. Historians now characterize the Haymarket trial as the nation’s first “red scare,” establishing a pattern of using isolated violence to justify systematic suppression of labor organizing that persists through COINTELPRO (1956-1971), PATRIOT Act surveillance (2001-present), and contemporary union-busting campaigns.