Origins and early activities
The RSDLP was not the first Russian
Marxist group; the
Emancipation of Labour group was formed in 1883. The RSDLP was created to oppose
narodnichestvo, revolutionary populism, which was later represented by the
Socialist-Revolutionary Party (SRs). The RSDLP program was based on the theories of
Karl Marx and
Friedrich Engels - that, despite Russia's agrarian nature, the true revolutionary potential lay with the industrial working class. The RSDLP was illegal for most of its existence; at the end of the
first party congress in March 1898, all nine delegates were arrested by the Imperial Russian Police. At this time there were 3 million Russian industrial workers, just 3% of the population.
Second Congress, a young intellectual named Vladimir Ilyich Ulyanov joined the party, better known by his pseudonym—
Vladimir Lenin. In 1902 he had published
What is to be Done?, outlining his view of the party's task and methodology—to form "the vanguard of the
proletariat." He advocated a disciplined, centralized party of committed activists who sought to fuse the underground struggle for political freedom with the class struggle of the proletariat.
In 1903, the Second Congress of the party met in exile in
Brussels to attempt to create a united force. However, after unprecedented attention from the Belgian authorities the congress moved to
London, meeting on August 11 in a chapel in
Tottenham Court Road.
 At the congress, the party split into two irreconcilable factions on November 17: the
Bolsheviks (derived from "Bolshinstvo"—
Russian for "majority"), headed by Lenin, and the
Mensheviks (from "Menshinstvo"—Russian for "minority"), headed by
Julius Martov. Confusingly, the Mensheviks were actually the larger faction, however the names Menshevik and Bolshevik were taken from a vote held at the 1903 party congress for the editorial board of the party newspaper,
Iskra ("Spark"), with the Bolsheviks being the majority and the Mensheviks being the minority. These were the names used by the factions for the rest of the party congress and these are the names retained after the split at the 1903 congress. Lenin's faction later ended up in the minority and remained smaller than the Mensheviks until the
Russian Revolution of 1917.
A central issue at the congress was the question of the definition of party membership. Martov proposed the formulation "A member of the Russian Social-Democratic Labour Party is one who accepts the Party’s programme, supports the Party financially, and renders it regular personal assistance under the direction of one of its organizations."
 Lenin, on the other hand, proposed a more strict definition: “A member of the Russian Social-Democratic Labour Party is one who accepts its programme and who supports the Party both financially and by personal participation in one of the Party organizations."
 Martov won the vote, and the bolsheviks accepted it as part of the adopted organizational rules.
Despite a number of attempts at reunification, the split proved permanent. As time passed, more ideological differences emerged. According to many historians
, the Bolsheviks pushed for an almost immediate "proletarian" revolution, while the Mensheviks believed that Russia was still at too early a stage in history for an immediate working-class revolution. The two warring factions both agreed that the coming revolution would primarily be "bourgeois democratic" in its character. But while the mensheviks viewed the liberals as the main ally, the bolsheviks opted for an alliance with the peasantry as the only way to carry out a popular revolution while defending the interests of the working class. Essentially, the difference was that the bolsheviks considered that in Russia, the tasks of the bourgeois democratic revolution would have to be carried out without the participation of the bourgeoisie.
Third Congress of the party (1905) was held separately by the Bolsheviks. The
Fourth Congress (1906) was held in
Sweden and saw a formal reunification of the two factions, (with the Mensheviks in the majority), but the discrepancies between Bolshevik and Menshevik views became particularly clear during the proceedings.
Fifth Congress of the party was held in
England, in 1907; it consolidated the supremacy of the Bolshevik faction and debated strategy for communist revolution in Russia. Stalin never later referred to his stay in London.
The Social Democrats (SDs) boycotted elections to the
First Duma (April–July 1906), but were represented in the
Second Duma (February–June 1907). With the SRs, they held 83 seats. The Second Duma was dissolved on the pretext of the discovery of an SD conspiracy to subvert the army. Under new electoral laws, the SD presence in the
Third Duma (1907–12) was reduced to 19. From the
Fourth Duma (1912–17), the SDs were finally and fully split. The Mensheviks had five members in the Duma and the Bolsheviks had seven, including
Roman Malinovsky, who was later uncovered as an
In the years of Tsarist repression that followed the defeat of the
1905 Russian Revolution, both the Bolshevik and Menshevik factions faced splits, causing further splits in the RSDLP, which manifested themselves from late 1908 and the years immediately following. The Mensheviks split into the "Pro-Party Mensheviks" led by
Georgi Plekhanov, who wished to maintain illegal underground work as well as legal work; and the Liquidators, whose most prominent advocates were
Nikolai Aleksandrovich Rozhkov and
Nikolay Chkheidze, who wished to pursue purely legal activities and who now repudiated illegal and underground work.
The Bolsheviks split threeways, into the Proletary group led by
Grigory Zinoviev and
Lev Kamenev, who waged a fierce struggle against the liquidators, ultimatists and recallists; the Ultimatist group led by
Grigory Aleksinsky, who wished to issue ultimatums to the RSDLP Duma deputies to follow the party line or to resign immediately; and the Recallist group led by
Alexander Bogdanov and
Anatoly Lunacharsky and supported by
Maxim Gorky, who called for the immediate recall of all RSDLP Duma deputies and a boycott of all legal work by the RSDLP, in favour of increased radical underground and illegal work.
There was also a non-faction group led by
Leon Trotsky, who denounced all the "factionalism" in the RSDLP, pushed for "unity" in the party, and focused more strongly on the problems of Russian workers and peasants on the ground. Although the Menshevik
Julius Martov was formally a liquidator, a lot of this was out of sentiment as a lot of his closest political friends were liquidators.
In January 1912, Lenin's Proletary Bolshevik group called a conference in Prague, and expelled the liquidators, ultimatists and recallists from the RSDLP, which officially led to the creation of a separate party, known as the
Russian Social Democratic Labour Party (bolshevik). In August 1912, Trotsky's group tried to reunite all the RSDLP factions into the same party at a conference in Vienna, but was largely rebuffed by the Bolsheviks.
 The Bolsheviks seized power during the
October Revolution in 1917 when all political power was transferred to the Soviets, and, in 1918, changed their name to the
(All-) Russian Communist Party. They banned the Mensheviks after the
Kronstadt Uprising of 1921.