Final answer:
Stalin's secret police, the NKVD, conducted mass arrests, executions, and sent millions to labor camps during the Great Purge. They orchestrated show trials and used propaganda to support Stalin’s policies, resulting in widespread fear and an atmosphere of suspicion throughout the Soviet Union.
Step-by-step explanation:
Stalin's secret police, primarily known as the NKVD, played an instrumental role in enforcing his reign of terror. Under his directive, millions of Soviet citizens were arrested on suspicions of disloyalty. Many faced execution or were sent to labor camps in Siberia without trials, with some labelled as "saboteurs" when factory accidents occurred. The secret police also executed members of the Red Army, including figures like Mikhail Tukhachevsky, a Marshal of the Soviet Union. Besides physical elimination, Stalin's apparatus used show trials and propaganda to discredit opposition, creating an atmosphere of fear and suspicion that permeated the Soviet society. As a result of the Great Purge, countless lives were lost, and the Soviet Union further descended into Stalin's authoritarian grip.