Complex sentence: White Terror in Russia refers to the violence carried out by the White Army during the Civil War (1917--23), beginning after the Soviet seizure of power in Moscow and Petrograd in November 1917 until the defeat of the White Army.
Split into simpler sentences: White Terror in Russia refers to the violence carried out by the White Army during the Civil War (1917--23). It began after the Soviet seized power over Moscow and Petrograd in November 1917 until the defeat of the White Army.