Welcome to this week’s History Thread! It’s May Day, so we’re going to discuss labor and the history of labor activism.

Today’s picture commemorates the famous Haymarket Riot in 1886, which led to May Day’s adoption as an international worker’s holiday; a strike in Chicago began on May 1st of that year, though the most famous event occurred three days later, when a bomb exploded during a demonstration, killing seven policemen; the police responded by firing into the crowd, killing four and wounding dozens more. Eight anarchists were convicted for the crime, even though their complicity was never conclusively proved.

The incident remained an important hingepoint for labor rights in the United States; it also led to an ongoing controversy over a statue commemorating the policemen killed in the bombing, which was periodically defaced and even dynamited by radical groups over the years. Eventually it was moved into the Chicago police headquarters, where it remains today. A Haymarket Martyrs’ Monument, designed to celebrate the strikers killed in the riot, was erected in nearby Forest Park in 1992.