The Communist Party of the Netherlands (, , CPN) was a Dutch communist party. The party was founded in 1909 as the Social-Democratic Party (SDP) and merged with the Pacifist Socialist Party, the Political Party of Radicals and the Evangelical People's Party in 1991, forming the centre-left GreenLeft. Members opposed to the merger founded the New Communist Party of the Netherlands. History Foundation In 1907, Jan Ceton, Willem van Ravesteyn, and David Wijnkoop of the Social Democratic Workers' Party (SDAP) founded ("The Tribune"), a magazine in which they criticized the party leadership. They maintained orthodox Marxist views and expected a proletarian revolution. They opposed the leadership of the SDAP, who were more oriented towards more a revisionist ideology and a parliamentary and reformist political strategy. At a party congress in Deventer held on February 14, 1909, SDAP leaders demanded that they stop publishing De Tribune or be expelled from the party. Wijnkoop and Ceton refused; they and their supporters, including the poet Herman Gorter and the mathematician Gerrit Mannoury, left to form a new party. This was the first such split in a Western European socialist party, although others followed. There had already been a split between the Bolsheviks and Mensheviks in the Russian Social Democratic Labour Party, and between the Bulgarian Workers' Social Democratic Party and the Tesnjaki ("Narrowist") group. On March 14, 1909, the dissenters founded the new Social Democratic Party (SDP). They had a membership of around 400 spread across different cities: Amsterdam (160), Rotterdam (65), The Hague (45), Leiden (56), Utrecht (25), Bussum (15). 1909–1922 In the 1910s the SDAP paid much attention to attacking the newly formed SDP. The mobilization for the First World War, which the SDAP supported and the SDP opposed, further strengthened the differences between the parties. In the 1917 elections the SDP was still unable to win any seats. In May 1918 the Left Wing founded the journal De Internationale, uniting four opposition groups within the SDP, with groups in Amsterdam, Rotterdam and The Hague plus the Zimmerwald Left Propaganda Union. This group did not favour the parliamentarianism of the majority. The Russian Revolution of 1917 fractured most European parties between their revolutionary and reformist factions; this had already happened in the Netherlands, but it profoundly changed the SDP. Previously a party of orthodox Marxist intellectuals with little working-class support, the SDP saw an influx of members coming from the free