According to the American historian Crane Brinton, a major social revolution may have some discernible periods. These include, for example, The Old Regime, a Moderate Phase, a Radical Phase, and a reactionary time called Thermidor.  Radical Phase: 1917-1921 which coincided with the whole duration of the Civil War in Russia, began with the seizure of power by the Bolsheviks, and it involved an armed power struggle between the Bolsheviks and several rival groups.