The International Workingmen's Association (IWA), often called the First International (1864–1876), was an international organisation which aimed at uniting a variety of different left-wing socialist, social democratic, communist and anarchist groups and trade unions that were based on the working class and class struggle. It was founded in 1864 in a workmen's meeting held in St. Martin's Hall, London. Its first congress was held in 1866 in Geneva. In Europe, a period of harsh reaction followed the widespread Revolutions of 1848. The next major phase of revolutionary activity began almost twenty years later with the founding of the IWA in 1864. At its peak, the IWA reported having 8 million members while police reported 5 million. In 1872, it split in two over conflicts between statist and anarchist factions and dissolved in 1876. The Second International was founded in 1889. Source: Wikipedia (en)