The Great Purge started with the arrests of party members, Bolsheviks, and members of the Red Army and then grew to include Soviet peasants, members of the intelligentsia, and members of certain nationalities.
During its mass operations, the NKVD widely utilized imprisonment, torture, violent interrogation, and arbitrary executions to solidify control over civilians through fear.
By 1938, however, the oppression had become so extensive that it was damaging the infrastructure, economy and even the armed forces of the Soviet state, prompting Stalin to wind the purge down. In November 1938 Beria succeeded Yezhov as NKVD head easing of the repression that begun under Yezhov.
The government officially admitted that there had been some injustice and "excesses" during the purges, which were blamed entirely on Yezhov and over 100,000 people were released from the labour camps. But the liberalization was only relative as arrests, torture and executions continued.