The article is devoted to a monument recently discovered in the Department of Manuscripts of the Library of the Academy of Sciences of Lithuania - the “Journal” of O.M. Tsyavlovsky. As a sergeant of the Life Guards of the Preobrazhensky Regiment, its author took part in the Archipelago expedition of the Russian Fleet of 1769-1774. The article examines the biography of O.M. Tsyavlovsky and the history of his family, gives an archaeographic characteristic of the manuscript. Special attention is paid to the characteristics of the unique information of the “Journal”, which describes the author’s voyage on the ship “George the Victorious” from Reval to the Aegean Sea, as well as the fate of the author after returning from the Archipelago.