International Workers’ Day is the commemoration of the May 4, 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 the police. The police responded 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 theExposition 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 the International’s second congress in 1891.
Subsequently, the May Day Riots of 1894 occurred. In 1904, the International Socialist Conference meeting in Amsterdam called on “all Social Democratic Party organizations and trade unions of all countries to demonstrate energetically on May First for the legal establishment of the 8-hour day, for the class demands of the proletariat, and for universal peace.” The congress made it “mandatory upon the proletarian organizations of all countries to stop work on May 1, wherever it is possible without injury to the workers.”