De-Cossackization (Russian: Расказачивание, Raskazachivaniye) was the Bolshevik policy of systematic repressions against Cossacks of the Russian Empire, especially of the Don and the Kuban, between 1919 and 1933 aimed at the elimination of the Cossacks as a distinct collectivity by exterminating the Cossack elite, coercing all other Cossacks into compliance and eliminating Cossack distinctness. The campaign began in March 1919 in response to growing Cossack insurgency. According to Nicolas Werth, one of the authors of The Black Book of Communism, Soviet leaders deciding to "eliminate, exterminate, and deport the population of a whole territory", which they had taken to calling the "Soviet Vendée". The de-Cossackization is sometimes described as a genocide of the Cossacks, although this view is disputed, with some historians asserting that this label is an exaggeration. The process has been described by scholar Peter Holquist as part of a "ruthless" and "radical attempt to eliminate undesirable social groups" that showed the Soviet regime's "dedication to social engineering". Throughout this period, the policy underwent significant modifications, which resulted in the "normalization" of Cossacks as a component part of Soviet society.
Cossacks were simultaneously both an ethnicity and a grouping of special social estates in the Russian Empire from the 16th to the early 20th century. Because of their military tradition, Cossack forces played an important role in Russia's wars of the 17th–20th centuries such as the Crimean War (1853–1856), the Napoleonic Wars, various Russo-Turkish Wars, and the First World War of 1914-1918. In the late-19th and early-20th centuries, the tsarist regime deployed Cossack detachments to perform police service and to suppress revolutionary movements, especially in 1905–1907.
Following the October Revolution of 1917, a conflict broke out between the new Bolshevik Communist regime in Russia and many Cossacks.