In which year did the Haymarket affair occur?

The Haymarket affair occurred in 1886, culminating in a bombing and gunfire at Chicago’s Haymarket Square on May 4.

The rally supported striking workers seeking an eight-hour workday. Police moved to disperse the peaceful meeting after a related confrontation at McCormick Harvesting Machine Company, where police had killed workers the previous day. An unknown person threw a bomb at the advancing police, triggering gunfire.

Seven police officers and at least four civilians died, while dozens were injured. Eight anarchists were prosecuted, although the trial did not establish which person threw the bomb. Four defendants were executed in 1887; Illinois Governor John Peter Altgeld pardoned the surviving defendants in 1893.

The event is often confused with the May 1 labor demonstrations that preceded it. Haymarket helped inspire international May Day observances, but the central affair itself took place on May 4, 1886.