When did the campaign of political  repression that Mikhail Demichev was arrested during occur?
Mikhail Demichev:  During the Great Purge, he was arrested on August 9, 1937 and later executed. Great Purge: The Great Purge or the Great Terror (Russian: Большо́й терро́р ) was a campaign of political repression in the Soviet Union which occurred from 1936 to 1938.
i don't know