The Prague Conference, officially the 6th All-Russian Conference of the Russian Social Democratic Labour Party, was held in Prague, Austria-Hungary (Present-Day Czechia), on 5–17 January 1912. Sixteen Bolsheviks and two Mensheviks attended, although Joseph Stalin and Yakov Sverdlov were unable to attend because they were in internal exile at the time, while 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 predominantly Bolshevik Russian Social Democratic Labour 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.