A. A. Gordeev is a hereditary Don Cossack, a colonel of the Don Army, a recipient of the Order of St. George, a participant in the First World War and the White movement. He created a comprehensive work on the history of the Cossacks of the Russian realm. The author studied the origins, development, political and military organization of the Cossacks, the system of governance, and the distinctive features of managing their economy, as well as the culture of everyday life. He described the hard, continuous wars fought by the Cossacks to protect their lands, as well as campaigns as part of Russian armies. He presented the historical fates of all Cossack hosts of the Russian Empire: the Don, Ural, Kuban, Terek, Orenburg, Astrakhan, Siberian, Semirechye, Transbaikal, Yenisei, Amur, and Ussuri Cossacks. Gordeev’s fundamental work has been highly praised by historians and by participants in the movement for the revival of Cossackdom.