Stalin used this tactic in the trials of the Bolsheviks. Coercion. Threats. Pre-planned denunciations. The Trial of the Twenty-One was one of the last of the Moscow trials. It took place in March 1938 during the end of the Great Purge by Josef Stalin, then leader of the Union of Soviet Socialist Republics. https://www.facebook.com/share/v/1EiNtFsqn7/