The deportation of the Crimean Tatars began on May 18, 1944 and lasted till early June.
The official reason for the deportation was the secret decision of the State Defence Committee No. 5859 "On Crimean Tatars" dated 11 May 1944, which accused Crimean Tatars of alleged mass treason and mass collaboration with the Hitler's troops during the occupation of Crimea. The act was undoubtedly the genocide and ethnocide, as evidenced by accusation of the people of treason and application of the principle of collective responsibility.
According to the official data, 183,144 Crimean Tatars were deported from Crimea. According to the Tatar sources, 228,500 Crimean Tatars were deported, of whom about 110,000 people died during first 18 months.