Short answers, pulled from the story.
The White Terror refers to violence and mass killings carried out by the White movement and its governments during the Russian Civil War, which lasted from 1917 to 1923. Unlike the Bolshevik Red Terror, which was formally proclaimed on the 5th of September 1918, the White Terror had no founding decree. Individual acts of anti-Bolshevik violence began by the end of 1917, with large-scale killing starting in early 1918.
Estimates vary widely. Dietrich Beyrau placed the death toll between 20,000 and 100,000 excluding pogrom victims, while Russian historian V. Erlikhman estimated 300,000 deaths. Nikita Ratkovsky believed the number exceeded 500,000 excluding pogroms. The 1920 Cheka trial of Kolchak's ministers recorded at least 25,000 executions in Yekaterinburg Governorate alone between 1918 and 1919.
Antisemitic pogroms were a significant component of violence during the Russian Civil War. The 1985 Whitaker Report of the United Nations cited 100,000 to 250,000 Jews killed in more than 2,000 pogroms by a mixture of Whites, Cossacks, and Ukrainian nationalists. Between 1918 and 1921, 1,236 pogroms were committed across 524 towns in Ukraine, with estimates of Jewish deaths in those attacks ranging from 30,000 to 60,000.
Historians like Nicolas Werth argued that the Red Terror was systematic, ideologically driven, and targeted entire social classes, while the White Terror was disorganized and carried out largely by unauthorized units. Others, including Peter Holquist and Joshua Sanborn, disputed this, arguing that White violence carried its own ideology, especially in its persecution of Jews. Unlike the Red Terror, the White Terror was never formally proclaimed by White leaders as state policy.
The White Terror was most acute in the Far East under Grigory Semyonov and Baron Roman von Ungern-Sternberg. Semyonov personally supervised torture chambers in Transbaikalia where some 6,500 people were murdered, and more than 1,600 were shot. Major General William S. Graves, who commanded North American occupation forces in Siberia, testified that anti-Bolshevik forces killed approximately one hundred people for every one killed by the Bolsheviks in Eastern Siberia.
Admiral Alexander Kolchak, who seized power in Siberia in November 1918, issued a decree on the 3rd of December 1918 revising the imperial criminal code to protect his rule. Bureaucratic sabotage became punishable by 15 to 20 years of hard labor, and a regulation adopted on the 11th of April 1919 imposed five years of prison on anyone deemed a threat due to ties with the Bolshevik revolt. Unauthorized return from exile carried a sentence of four to eight years at hard labor.