Mannerheim Line - Soviet Intelligence

Soviet Intelligence

Soviet intelligence worked in Finland on multiple levels. The Finnish communist party, running in the Soviet Union, had its own military line to the Central Committee. Its intelligence concentrated on the Finnish army, taking notes on the locations of Finnish artillery and defensive positions. The most important Soviet intelligence organisations in Finland were the NKVD and the Fourth Department of the Army General Staff. Leningrad Military District, the Baltic Fleet and border troops under the NKVD, conducted espionage operations.

The Finns exposed two espionage cases during the 1930s. Vilho Pentikäinen, a photographer serving on the Finnish general Staff, escaped to the Soviet Union in 1933. The second case was of Simo Haukka; he took photographs and measured roads and terrain for Soviet intelligence in 1935.

Soviet intelligence published a top-secret and very detailed photobook of the Finnish terrain and fortifications in 1938. The book included a seven page report and 22 pages of maps and photographs. Every issue was numbered, running probably only into dozens. Soviet intelligence activity increased in 1938 and expanded still further in 1939. Before the start of the Winter War, Soviet intelligence published a book for Red Army officers. It was called "Finland. Written Description of March Routes". It was later translated and republished as the "Red Army March Guide to Finland". The guide included over 200 pages of maps and photographs.

Along with the intelligence, the Soviet Union received a detailed map of the defences on the Isthmus. A German military attaché in Helsinki, General Arniké, handed it over in Moscow in September 1939.