The primary purpose of the Haymarket Affair in 1886 was to advocate for the eight-hour workday and to promote labor rights in the United States. The event, which began as a peaceful rally in Chicago supporting striking workers, ended in violence when a bomb was thrown at police, resulting in deaths and injuries. The incident led to a public backlash against labor movements, and several anarchists were subsequently arrested and executed. The Haymarket Affair remains significant in labor history, symbolizing the struggle for workers' rights and the complex relationship between labor movements and the state.