The Prague Conference, officially the 6th All-Russian Conference of the Russian Social Democratic Labour Party, was held in Prague, Austria-Hungary on 5–17 January 1912. Eighteen Bolsheviks attended, although Joseph Stalin and Yakov Sverdlov, who were in exile at the time, were not able to. Georgi Plekhanov claimed he was too ill to attend. At the conference, Vladimir Lenin and his supporters broke away from the rest of the Russian Social Democratic Labour Party and formed their own, purely Bolshevik, party. The conference was meant to be secret; Lenin had instructed: "No-one, no organisation must know about this". However, every detail was known to the Okhrana, the secret police of the Russian Empire.