Why was Lenin's leadership crucial to the success of the Russian Revolution?

Not long after the Bolsheviks had seized power in 1917, Vladimir Ilyich Lenin filled out a bureaucratic questionnaire. For occupation, he wrote "man of letters." So it was that a son of the Russian intelligentsia, a radical straight from the pages of Dostoyevsky’s novel The Possessed, became the author of mass terror and the first concentration camps ever built on the European Continent.