Decossackization (Russian: Расказачивание, Raskazachivaniye) was the Bolshevik policy of systematic repressions against Cossacks of the Russian Empire, especially of the Don and the Kuban, between 1917 and 1933 aimed at the elimination of the Cossacks as a separate ethnic, political, and economic entity.
Many authors characterize decossackization as genocide of the Cossacks, while others reject this characterization. For example, Peter Holquist, a specialist of the conflict in the Don region, concludes that decossackization did not constitute an "open-ended program of genocide" but rather was a "ruthless" and "radical attempt to eliminate undesirable social groups," which showed the Soviet regime's "dedication to social engineering." On the other hand, Shane O' Rourke, a specialist in Cossack history, concludes that decossackization did constitute a genocide of the Cossack people.
Cossacks were simultaneously both an ethnicity and special social estates in the Russian Empire from the 16th to the early 20th century. There were two different estates in the Russian empire. The part of the descendants of the former Cossacks of Ukrainian regiments were the less numerous civil estate of Cossacks. Any Russian empire population census allowed these Cossacks only to mention "a Cossack" as their civil estate. They did not serve in either the Cossack Hosts or the Cossack commands. Other Cossacks had dual estate. They belonged both to some civil estate and to the Cossack military estate. Though their Cossack estate was a military secret many Cossacks violated their obligations to keep this secret and mentioned "Cossack" as their social civil estate during any population census in the Russian empire to distinguish themselves from "usual peasants and soldiers". There was decossackization in the Russian empire during which many Cossacks lost their military estate and turned, as Yakiv Markovich wrote, into "the peaceful dwellers". The majority of the Cossack military estate members belonged to the civil estate of "village dwellers" (peasants). This is why General Lavr Kornilov described himself as the son of "a Cossack and a peasant". When his father had left the peasant estate because of his promotion to nobility, he did not leave the Cossack military estate in any way. But Cossacks had privileges in contrast to usual peasants. Non-Cossack peasants had the status of aliens in the Cossack regions and villages. The alien community and the Cossack community were different ones with distinct land properties in any Cossack town and village.Cossack hosts performed the duty of border guards and settled in the Russian borderlands of the times: in southern Russia in the Don and Kuban areas, as well as parts of Siberia and Central Asia such as Orenburg and Transbaikalia. 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, Napoleonic Wars, various Russo-Turkish Wars, and the First World War. In the late 19th and early 20th centuries, the tsarist regime employed them extensively to perform police service and suppress the revolutionary movement, especially in 1905–07.