Bolsheviks formed part of the Red Army. They started a provisional government that led to the formation of communism and the Soviet Union in Russia. This group represents the end for the Russian Empire, and henceforth they controled the Russian Revolution.
Their role during the Russian Revolution was related to the Romanov Royal Family. Tsar Nicholas II possessed the title of Russian Emperor at that time, he was assassinated with his entire family by the Bolsheviks in 1917. This monarch had rather incompetent counselors, they aimed the tsar to kill people unfairly and stop attending their major problems- such as hungry. Bolsheviks presented themselves as the people's deffensors, and ended with the prestige and richness of not only royal family but nobles. Their provisional government was not rather stable, it took quite a while to stablish a Soviet Union.