The Haymarket Affair, also known as the Haymarket Riot, occurred on May 4, 1886, in Chicago. It began as a peaceful rally in support of workers striking for an eight-hour workday. The event turned violent when a bomb was thrown at police, leading to a chaotic confrontation that resulted in the deaths of several police officers and civilians. In the aftermath, the incident sparked widespread outrage and led to the arrest of several anarchists, culminating in a controversial trial. The Haymarket Affair became a symbol of the labor movement and highlighted the struggles for workers' rights in the United States.