Civil War 1919-1921
The Civil War consisted of the Bolshevik 'Reds' and the Anti-Communist 'Whites'. The 'Whites' were mainly Tsarist Officers, Cossacks, Bourgeoisie, Outlawed Politic Groups (Mensheviks), International Community. The 'Reds' had huge advantages though; they were more centralized, were more organized, controlled the industry and had the majority of the population because they were made up of the lower classes. The 'Whites' were attacking on many fronts and their attacks were halfhearted. The majority of the peasants remained neutral because The 'Reds' won the Civil War but had sent their Nation into turmoil, it needed to recover.
Summary
The Bolsheviks won because they were much more organized and had control of the industry as well as the railroads. At the end of the war the nation was having huge economical issues and needed a massive recovery.