The Case of the Trotskyist Anti-Soviet Military Organization, also known as the Military Case or the Tukhachevsky Case, was a 1937 secret trial of the high command of the Red Army, a part of the Great Purge.

The Great Purge or the Great Terror (Russian: Большой террор), also known as the Year of '37 (37-ой год, Tridtsat sedmoi god) and the Yezhovshchina ('period of Yezhov'), was Soviet General Secretary Joseph Stalin's campaign to solidify his power over the party and the state; the purges were also designed to remove the remaining influence of Leon Trotsky as well as other prominent political rivals within the party. It occurred from August 1936 to March 1938.Following the death of Vladimir Lenin in 1924 a power vacuum opened in the Communist Party. Various established figures in Lenin's government attempted to succeed him. Joseph Stalin, the party's General Secretary, would outmaneuver political opponents and ultimately gain control of the Communist Party by 1928. Initially Stalin's leadership was widely accepted, and the doctrine Socialism in One Country became enshrined party policy. However, by the early 1930s party officials began losing faith in his leadership following the disasters of collectivization and the limited success of the First Five-Year Plan. These policy failures led to Stalin's rivals such as Leon Trotsky attempt to sway the party away from Stalin's command.

In this atmosphere of doubt and suspicion, a popular high-ranking official, Sergei Kirov, was assassinated in 1934. His death spearheaded an investigation that revealed a network of party members working against Stalin including several of Stalin's rivals. Many of those arrested in Kirov's assassination had also confessed plans to kill Stalin himself, including high-ranking party officials. Historians doubt the validity of these claims; nonetheless, they do agree that Kirov's death was the flashpoint where Stalin would take action and begin the purges.By 1936 Stalin's paranoia reached a crescendo. The fear of losing his position, the potential return of Trotsky, and the rising threat of fascism from the west, goaded him into authorizing the Great Purge. The purges themselves were largely conducted by the NKVD (People's Commissariat for Internal Affairs), the secret police of the USSR. The initial stages of the purges were targeted at the Soviet government itself. The NKVD began the removal of the central party leadership, Old Bolsheviks, government officials, and regional party bosses. Eventually the purges were expanded to the Red Army and military high command which would have a disastrous effect on the military altogether. As the scope of the purge began widening, the omnipresent suspicion of saboteurs and counter-revolutionaries began impacting civilian life. The NKVD began targeting certain ethnic minorities such as the Volga Germans, who were subjected to forced deportation and extreme repression. During the purge, the NKVD widely utilized imprisonment, torture, violent interrogation, and arbitrary executions to solidify control over civilians through fear.In 1938 Stalin reversed his stance on the purges and declared that the internal enemies had been removed. Stalin criticized the NKVD for carrying out mass executions and subsequently executed Genrikh Yagoda and Nikolay Yezhov who headed the NKVD during the purge years. Despite the Great Purge being over, the atmosphere of mistrust and widespread surveillance continued for decades after. Scholars estimate the death toll for the Great Purge (1936–1938) to be roughly 700,000. The term great purge itself was popularized by the historian Robert Conquest in his 1968 book The Great Terror. Conquest's title itself was an allusion to the period from the French Revolution known as the Reign of Terror.