The Russian Social Democratic Party split into two factions at its London Conference in 1903. The majority faction at the conference was led by Vladimir Ilyich Ulyanov (Lenin). The Russian for Majority is Bolshevik = bigger. In Russia itself Lenin's faction was probably not a majority. The Minority was known as Menshevik. The two groups became separate parties. Lenin's adapted itself to conspiratorial and violent politics. The Mensheviks remained a largely moderate and legal party.

In the immediate aftermath of the first revolution in 1917 after the abdication of the Tsar the Menshevik faction led the provisional government, and proposed a moderate policy of evolving towards a western European democratic mode of government. However they were overthrown in the October Revolution by Lenin's Bolsheviks who then suppressed all opposition.

Stalin renamed them the Communist party in 1921.

See Russia and Soviet Union.

Was it the original of the Single Political Parties which characterised dictatorships in the 20th century (and continues into the 21st)?