What event led to the rise of communism in Russia?

Russia's communists had recently spilt into two different parties.

The real event that led to the rise of "communism" in Russia was the October Revolution led by Vladimir Lenin and the Bolshevik Party. The word communism is in quotes because true communism was never achieved in Russia. Lenin and his followers imposed socialism, not communism.

The split of the Marxist party into two factions, Bolshevik and Menshevik, did not lead to the rise of communism, because that split took place in 1903. Further, that split was a split within a Marxist political party, so both factions had socialism/communism as their aims.