The aim of the article is to determine the role of an artillery officer Sergey Izenbek in naval cooperation between Russia and
Great Britain in 1916–1917. The Russian State Archive of the Navy has Izenbek’s personal fund, which contains his diary. Izenbek
kept it from the beginning of September of 1916 when he left for London till the spring of 1917 when he got the warrant to leave
Great Britain and return to Russia. This diary has not become the subject of a separate study although it deserves it. The fund also
contains Izenbek’s other documents including his service record, letters and reports. Using source analysis methods, the authors study the diary as a source on the history of naval cooperation between Russia and Great Britain. The article pays special attention to the study of the Russian-British relations and the role the Naval General Staff played in them. On the eve of World War I, it belonged to the main centres responsible for establishing the Russian-British relations in the naval sphere. Gradual rapprochement of the two countries that began after the end of the Russian-Japanese war made the Naval General Staff contribute to the process thus overcoming the war-caused high level of distrust. The Staff was responsible for the preparation of war plans. It had its own representatives— naval agents—in several states. With the outbreak of World War I, the exchange of scientific and technical information between Russia and Great Britain sharply intensified. Both sides showed interest in it. If earlier the main role in this process was assigned to naval
agents, in the time of war, the countries began to exchange their officers who were experts in certain types of weapons. One of them was Sergey Izenbek. The Naval General Staff sent Izenbek to the Grand Fleet as a special representative of the Russian Navy with the task of studying the British experience in the field of improving artillery armament and its application. He coped with the task brilliantly. He collected the information about the state of artillery armament, the level of training of the personnel, the tactics of shooting and sent it to the Staff. He participated in the talks on the exchange of the latest weapons and visited the factories that produced them. The diary also shows the interest of the British in the experience of the Russian Navy: how they adopted it and how the idea of the desirability of its implementation by the British Navy gradually won its supporters. Shortly before his return to Russia, Izenbek witnessed the implementation. In general, Izenbek’s diary demonstrates that the cooperation between Russia and Great Britain in the naval sphere during World War I was useful to both the sides.