Short answers, pulled from the story.
Large-scale White Terror violence started in early 1918 and continued until the defeat of the Whites from 1920 to 1922. Individual acts of violence against Bolshevik rule began by the end of 1917 before evolving into mass killings.
Warlords like Grigory Semyonov and Baron Roman von Ungern-Sternberg led the most acute phase of violence in the Far East. Admiral Alexander Kolchak pursued persecution policies after seizing power in Siberia in November 1918 while Denikin's army conducted numerous pogroms.
Dietrich Beyrau estimates victims between 20,000 and 100,000 excluding pogrom victims compared to up to 1.3 million for the Red Terror. Nikita Ratkovsky believes victim numbers may exceed 500,000 excluding pogroms while Ronald Suny states casualties likely fall between 50,000 and 140,000 if restricted to White movement atrocities.
His government issued a decree on the 3rd of December 1918 revising criminal code articles to preserve the Supreme Ruler system. Regulation 428 adopted the 11th of April 1919 provided five-year prison terms for individuals considered threats due to Bolshevik ties.
Russian historians hold conflicting views on whether the White Terror was premeditated state policy or spontaneous chaos. Western historians like Richard Pipes and Nicolas Werth contrasted the two terrors claiming the White version was restorative and arbitrary rather than ideological while Peter Holquist and Joshua Sanborn argue it had its own ideological underpinnings similar to German Freikorps ethos.