The Moscow Trials were a series of trials in 1936, 1937 and 1938 in the Soviet Union which were the precursors to the Great Purge.
There were three major trials in the Moscow Trials, the Trial of the Sixteen, the Trial of the Anti-Soviet Trotskyist Center, and the Trial of the Twenty-One.
The defendants included most of the surviving Old Bolsheviks, as well as the leadership of the Soviet secret police. Most defendants were charged under Article 58 of the RSFSR Penal Code with conspiring with the western powers to assassinate Stalin and other Soviet leaders, dismember the Soviet Union, and restore capitalism.
Read more about Moscow Trials: Background, Trial of The Sixteen, Trial of The Anti-Soviet Trotskyist Center, Trial of The Generals and The Tukhachevsky Affair, Trial of The Twenty-One, Aftermath, Legacy, Trials in Literature