On June 11, 1937, following a secret trial, eight senior Red Army officers were executed for purportedly conspiring against the regime of Soviet leader Joseph Stalin. In the aftermath, a purge was carried out throughout the Red Army echelons, which resulted in 37,761 officers and commissars dismissed from the service, 10,868 arrested and 7,211 condemned for anti-Soviet crimes.
The suppression of the Red Army was only one aspect of the Great Purge, which included Communist Party and government officials, repression of wealthy landlords, widespread police surveillance, suspicion of saboteurs, counter-revolutionaries, imprisonment, and arbitrary executions. Between 1937-1938 which was the peak of the purge, between 700,000 and 1.2 million people were killed.
The purge of the Red Army affected 3 of the 5 Field Marshals , 13 of 15 Army commanders, 8 of 9 Admirals, 50 of 57 Army Corps commanders, and 154 of 186 divisional commanders; a total of 34,000 officers were sent to labor camps in Siberia or were executed. As a result of the sheer number affected, by 1939, very few in the Soviet High Command and newly appointed officers who had been promoted more for party loyalty than military competence, knew how to implement the Red Army’s Deep Battle in actual warfare. The Deep Battle concept was the main Soviet offensive strategy that envisioned coordinated use of massive land, sea, and air power to advance deep and quickly inside enemy territory to achieve complete tactical and strategic victory.