Fortifications of the Western Borderland of the Soviet Union between 1918–1939

Abstract

In this article, the author explores the permanent fortifications known as the “Fortified Districts”, and unofficially as the “Stalin Line”, which were established on the western borderland of the Soviet Union between 1929 and 1939. The Soviet theory of developing a fortification system along the entire western borderland envisaged protection of the most important operational and strategic directions: Leningrad, Moscow, and Kiev. According to Soviet plans, the basis for the line of fortifications was the Fortified Districts. In terms of manpower, they were equivalent to an infantry brigade, with powerful firing assets matching those of a corps. Overall, a typical Fortified District ranged from 100 to 180 km in length (140 on average) and from 30 to 50 km in depth (42 on average), and was varied in nature. The “Stalin Line” was built between 1929 and 1939, and this period can be divided into two distinctive phases, namely: the first, covering years from 1931 to 1934, which witnessed the construction of the first thirteen Fortified Districts, fully equipped where possible; the second period, covering the years from 1936 to 1939, when a decision was made to close the gaps existing between the thirteen Fortified Districts by adding eight more, to further reinforce the fortifications by placing heavy artillery in the flanking bunkers, and to complete the formation of the fireteams. The development of the fortified districts lasted probably until the end of August 1939, after which it was stopped on the explicit orders of Joseph Stalin. It is reasonable to believe that this decision originated, among others, in the signing of the Molotov–Ribbentrop Pact on 23 August 1939. At the same time, it can be concluded that the eastern neighbour of Poland, who on 17 September 1939 became its aggressor, had a well-developed fortification system along its western border. Starting with 28 June 1940, it constituted a new line of fortifications known as the “Molotov Line”.