Abstract. The article deals with participation of Cossacks military groups in suppression of Russian Revolution of 1905. It based on the Letter of group of Cossacks who were lodged in Moscow during the Revolution. The Letter is keeping in the fund of S.P. Melgunov in the Archive of the Russian Academy of Sciences. Its content allows to reconstruct ideas and sentiments of different representatives of the Cossack society, who lived in Moscow, in the period of tragic revolutionary events of 1905. This information adds historical sources about the Don history, and it can be used both for research and for educational aims.
Keywords: Cossacks, letter, Revolution of 1905, Moscow, Archive of the Russian Academy of Sciences, history