International Workers' Day is the commemoration of the 1886 Haymarket affair in Chicago. The police were trying to disperse a public assembly during a general strike for the eight-hour workday, when an unidentified person threw a bomb at them. The police reacted by firing on the workers, killing four demonstrators. "Reliable witnesses testified that all the pistol flashes came from the center of the street, where the police were standing, and none from the crowd. Moreover, initial newspaper reports made no mention of firing by civilians. A telegraph pole at the scene was filled with bullet holes, all coming from the direction of the police."
In 1889, the first congress of the Second International, meeting in Paris for the centennial of the French Revolution and the Exposition Universelle, following a proposal by Raymond Lavigne, called for international demonstrations on the 1890 anniversary of the Chicago protests. May Day was formally recognized as an annual event at t