In 1917 Lieutenant Kravkov completed navigation courses in Sevastopol and obtained the rank of Navigator First Class. In 1918 he was transferred to the Odessa Hydrographic Department. In November 1919 he set out from Odessa to Vladivostok on the transport ship "Iyerusalim". In Vladivostok he sided with the Red Army. During the Japanese intervention in Siberia he went underground.