At the Second Congress of the Social Democratic Labour Party in London in 1903, there was a dispute between Lenin and Julius Martov. Lenin argued for a small party of professional revolutionaries with a large fringe of non-party sympathizers and supporters. Martov disagreed believing it was better to have a large party of activists. Martov won the vote 28-23 but Lenin was unwilling to accept the result and formed a faction known as the Bolsheviks. Those who remained loyal to Martov became known as Mensheviks.
Those who joined the Bolsheviks included Krupskaya, Gregory Zinoviev, Joseph Stalin, Anatoli Lunacharsky, Mikhail Lashevich, Alexei Rykov, Yakov Sverdlov, Mikhail Frunze, Maxim Litvinov, Vladimir Antonov, Felix Dzerzhinsky, Gregory Ordzhonikidze, and Alexander Bogdanov.
During the First World War Krupskaya and Vladimir Lenin lived in Switzerland. After the overthrow of Nicholas II in April, 1917, they returned to Russia. Lenin now joined with Leon Trotsky in plotting against the government being led by Alexander Kerensky. When the Provisional Government collapsed in October, Lenin and the Bolsheviks took control of Russia.
Krupskaya had opposed Lenin's calls for an early revolution but after its success she hid her political differences with her husband. In November, 1917, Krupskaya was appointed to serve under Anatoli Lunacharsky as Deputy People's Commissar of Education and Enlightenment.
Lenin's health declined after being shot by Dora Kaplan on 30th August, 1918. Two bullets entered his body and it was too dangerous to remove them. Lenin suffered a stroke in May, 1922 and a second one in December, 1922. Four days later he dictated his famous 'testament' where he assessed all the main party leaders.
Three days after writing this testament Lenin had a third stroke. Lenin was no longer able to speak or write and although he lived for another ten months, he ceased to exist as a power within the Soviet Union.
Krupskaya published her memoirs, Reminisces on Lenin in 1926. Nadezhda Krupskaya died on 27th February, 1939.