The Haymarket affair (also known as the Haymarket riot or Haymarket massacre) on Tuesay 4 May 1886 in Chicago, began as a rally which became violent and was followed later by internationally publicized legal proceedings. An unknown person threw a bomb at police as they marched to disperse a public meeting in support of striking workers. The bomb blast and ensuing gunfire resulted in the deaths of seven police officers and an unknown number of civilians. Eight anarchists were tried for murder. Four were put to death, and one committed suicide in prison.