The growth of American industrial might in the 1870s and 1880s was paralleled by the emergence of unions representing the workers. Foremost among the early labor organizations was the Knights of Labor, which listed more than 700,000 members by the mid-1880s. Working conditions at the time were abysmal—little concern for safety existed in most factories, pay was low, benefits were nonexistent and the work day was often 10 to 12 hours, six days a week. The immediate focus of the K.O.L. and other unions was to achieve the eight-hour day. On May Day 1886, the workers at the McCormick Harvesting Machine Co. in Chicago began a strike in the hope of gaining a shorter work day. On May 3, police were used to protect strikebreakers and a scuffle broke out; one person was killed and several others injured. The following day, May 4, a large rally was planned by anarchist leaders to protest alleged police brutality. A crowd of 20,000 demonstrators was anticipated at Haymarket Square, where area farmers traditionally sold their produce. Rain and unseasonable cold kept the numbers down to between 1,500 to 2,000. The gathering was peaceful until a police official, in contravention of the mayor's instructions, sent units into the crowd to force it to disperse. At that juncture, a pipe bomb was thrown into the police ranks; the explosion took the lives of seven policemen and injured more than 60 others. The police fired into the crowd of workers, killing four. A period of panic and overreaction followed in Chicago. Hundreds of works were detained; some were beaten during interrogation and a number of forced confessions was obtained. In the end, eight anarchists were put on trial and seven were convicted of conspiracy to commit murder. Four were hanged in November 1887, one committed suicide and three were later pardoned by Illinois governor, John Peter Altgeld. Clearly the ranks of the Knights of Labor and other unions were filled with many socialists and anarchists; some were committed to violent disruption of the capitalist system. However, no evidence was provided at the time, nor has any been discovered since, which connected the eight convicted workers to the bomb-throwing. Widespread fear of unionism and other radicalism influenced most of the public to support harsh treatment of the accused. The Haymarket Riot was a signal event in the early history of American labor. It was largely responsible for delaying acceptance of the eight-hour day, as workers deserted the K.O.L. and moved toward the more moderate American Federation of Labor. For many years the police at Haymarket Square were regarded as martyrs and the workers as violent anarchists; that view moderated to a large extent in later times.