The Social Democratic Party of Lithuania (LSDP) was founded on 1 May (19 April O.S.) 1896 at a secret congress held in an apartment in Vilnius. Among the 13 delegates were Andrius Domaševičius and Alfonsas Moravskis — a pair of intellectuals regarded as the central organizers of the new political entity — and the future President of Lithuania, Kazys Grinius, as well as a number of worker activists. Also in attendance as a representative of the radical youth movement was an 18-year-old ethnic Pole named Felix Dzerzhinsky, later the head of the Soviet secret police. As Lithuania was then part of the Russian Empire, the LSDP was inevitably an illegal organization, meeting in secret and seeking to bring about the revolutionary overthrow of the Tsarist regime.