Melvyn Bragg and guests discuss the notorious attack of 4th of May 1886 at a workers rally in Chicago when somebody threw a bomb that killed a policeman, Mathias J. Degan. The chaotic shooting that followed left more people dead and sent shockwaves across America and Europe. This was in Haymarket Square at a protest for an eight hour working day following a call for a general strike and the police killing of striking workers the day before, at a time when labour relations in America were marked by violent conflict. The bomber was never identified but two of the speakers at the rally, both of then anarchists and six of their supporters were accused of inciting murder. Four of them, George Engel, Adolph Fischer, Albert Parsons, and August Spies were hanged on 11th November 1887 only to be pardoned in the following years while a fifth, Louis Ling, had killed himself after he was convicted. The May International Workers Day was created in their memory.