Plan East

Plan East (Plan Wschód) was a Polish defensive military plan, created in the 1920s and 1930s in case of war with the Soviet Union. Unlike Plan Zachód (Plan West), it was being prepared during the whole Interwar period, as the government of the Second Polish Republic treated the Soviet Union as the greatest potential military threat, capable of initiating a full-scale war. However, a handful of loose historical documents are all that remains of the original Plan East today.

Introduction
Since its establishment following World War I, the Second Polish Republic had been involved in wars and conflicts with almost all of its neighbors (see: Polish-Soviet War, Polish-Ukrainian War, Polish-Lithuanian War, Greater Poland Uprising, Silesian Uprisings, Border conflicts between Poland and Czechoslovakia). However, of these countries, only two were considered major threats — Germany and the Soviet Union.

During the 1920s and 1930s, the leaders of the Republic focused their efforts on countering the potential threat from the East. Fresh were memories of the Polish-Soviet War and the Battle of Warsaw, which saved both Poland and Europe from the spread of Bolshevik revolution by force. Both the Polish Army and the government in Warsaw were certain that war with the Soviets was inevitable, thus preparations for it were far more advanced than preparation for armed conflict with Germany. Only after 1935, when Nazi anti-Polish propaganda increased, did the threat posed by Poland's western neighbor become visible enough for Army planners to begin drawing up Plan West. Still, even by 1939, completed fortifications on the Eastern border of Poland vastly outnumbered those in the West.

The interbellum Polish-Soviet border
Poland's shared border with the Soviet Union was 1,412 kilometers long. By comparison, the border with Germany and its province of East Prussia was more than 20 percent longer, at 1,912 km. Neither border contained any major geographical obstacles, making defense very difficult.

In the north there was a flat, plain land with huge forests (e.g. Puszcza Nalibocka — the Wilderness of Naliboki). In addition, a major rail route connecting Moscow to Western Europe extended across the northern portion of the country. The areas major conurbation at the time was Wilno, located in the northeast corner of interbellum Poland.

The centre region of the country was primarily composed of a huge, sparsely populated swamp known as Polesie. This land had no roads and few rail lines. However, it held supreme strategic importance, as its landscape made possible a prolonged, organized defense. Neither Polesie nor the adjacent Volhynia contained any major urban centers.

The south, formerly a portion of the Galicia province of the Austrian Empire, was the most highly developed, with a high density of rail lines, growing industry (e.g., oil fields in Boryslaw), and the well-developed agriculture of Podolia. Lwów, one of the major urban centers of interbellum Poland, was located in this area. In addition, the Soviet border was marked by a natural obstacle — the Zbrucz river.

Virtually all Polish industrial and urban centers were located in the West. This made long-lasting defense possible, as a Soviet force would have taken up to several weeks to reach Upper Silesia, Warsaw, Kraków or Poznań. While devising Plan Wschód, Polish planners assumed cooperation and support would be forthcoming from Romania, which was Poland's main ally in the East.

Eastern border conflicts
The Soviet government undermined the validity of the Riga Peace Treaty, the treaty that had been signed by Moscow in 1921, from the outset. In the early 1920s the Soviets on several occasions organized guerrilla attacks on Polish settlements close to the border. The most famous of these was the attack on Stolpce, which took place on the night of August 3-4, 1924. This event prompted the creation of the Korpus Ochrony Pogranicza (Border Protection Corps). Such attacks continued throughout the 1920s, but reduced in scale during the 1930s, particularly after the signing of the 1932 Soviet-Polish Non-Aggression Pact.

Inception of Plan East
No copy of the plan has been preserved. All that is known are the basic precepts; restoring the whole plan is impossible. Work on the document was completed on February 4, 1939. The plan was based on the notions of Józef Piłsudski, who, until his death in 1935, was sure that war would arrive from the East. Thus most army maneuvers and field fortifications were held in the east, while Poland's western border was, to a large extent, neglected. To this day, some of these fortifications can be seen in the area around Sarny (see Sarny Fortified Area). Bunkers built by Polish Corps of Engineers in the 1930s were used in late 1940s by the Ukrainian Insurgent Army in their guerilla skirmishes with Red Army.

Polish planners were well aware that the Red Army was in many elements superior to their own. Therefore, the main idea was to organize a so-called "resistance in motion", and to try to split Soviet forces south and north of the vast Polesie swamps. Frontline armies, located in the vicinity of the border, were to try to delay the advance of the aggressors and to bleed them, while reserves, located mostly in the area of Brześć nad Bugiem and Lublin, were intended to enter the conflict in later stages. The Poles were expecting the Red Army to advance in three directions. Firstly, along the Minsk - Baranowicze - Białystok - Warsaw rail line. Secondly, along the Sarny - Kowel - Lublin line, and finally, in the south along the Tarnopol - Lwów line.

Structure of the Polish Army in the East
According to Polish historian Rajmund Szubański, in case of war in the East, the bulk of the Polish Army was supposed to have been concentrated both in the north and south, with central section of the border left mostly unguarded. Some military historians claim today that Polish planners placed too many units close to the border, which would have resulted in their total destruction in the opening days of the conflict. In contrast, rear positions were inadequately protected..

Front-line units
Seidner outlines the deployment:


 * In the extreme north-east, around the rail nexus of Mołodeczno, was Armia Wilno, which possibly consisted of three infantry divisions (1st Legions Infantry Division from Wilno, 19th Infantry Division, also from Wilno, 29th Infatry Division from Grodno), two Cavalry Brigades (Wileńska Cavalry Brigade from Wilno, Suwalska Cavalry Brigade from Suwałki), and the 5th Air Corps from Lida.
 * South of Armia Wilno was Armia Baranowicze, probably comprising four infantry divisions (9th Infantry Division from Siedlce, 20th Infantry Division from Baranowicze, 18th Infantry Division from Łomża, and 28th Infantry Division from Warszawa), two cavalry brigades (Nowogródzka Cavalry Brigade from Baranowicze, Podlaska Cavalry Brigade from Białystok) and the 4th Air Corps from Toruń.
 * In the center was Armia Polesie (also called Independent Operational Group Polesie). It was possibly composed of three infantry divisions (8th Infantry Division from Modlin, 27th Infantry Division from Kowel, 30th Infantry Division from Kobryń), one cavalry brigade (Mazowiecka Cavalry Brigade from Warszawa), Riverine Flotilla of the Polish Navy and the 3rd Air Corps from Poznań.
 * Further south was Armia Wołyń - three infantry divisions (2nd Legions Infantry Division from Kielce, 3rd Legions Infantry Division from Zamość, 13th Infantry Division from Równe), one cavalry brigade (Wołyńska Cavalry Brigade from Równe) and the 2nd Air Corps from Kraków.
 * In the extreme south was Armia Podole - five infantry divisions (5th Infantry Division from Lwów, 11th Infantry Division from Stanisławów, 12th Infantry Division from Tarnopol, 22nd Infantry Division from Przemyśl, 24th Infantry Division from Jarosław), two cavalry brigades (Podolska Cavalry Brigade from Stanisławów, Kresowa Cavalry Brigade from Brody) and the 6th Air Corps from Lwów.

Apart from these units, in all armies there were Border-Area Defence Corps units and garrisons of the main cities.

Reserve forces

 * Behind Armia Wilno and Armia Baranowicze was Armia Lida, consisting of three Infantry Divisions.
 * Behind Armia Podole and Armia Wołyń was Armia Lwów, made up of two Infantry Divisions and a Cavalry Brigade (5th Krakowska BK from Kraków).
 * Far behind the frontlines, around the city of Brzesc, was the main reserve, which probably comprised six IDs, two Cavalry Brigades (7th Wielkopolska BK from Poznań, 8th Pomorska BK from Bydgoszcz), an Armored Brigade and the 1st Warsaw Air Corps.

The Red Army and its units along the Polish border
In the mid-1930s, the Soviet government started an immense armament program, which resulted in a rapid increase in the number of units. The number of tanks and airplanes along the Polish border grew significantly, and the Soviets enjoyed superiority in all elements. Polish planners anticipated that the Soviets had three times as many soldiers as their own army. The Soviets' superiority in tanks and airplanes was not estimated, but the disproportion was immense. In August 1939 along the Polish border there were likely as many as 173 Red Army infantry divisions (see: Soviet order of battle for invasion of Poland in 1939).

September 1939
On September 1, 1939, Nazi Germany attacked Poland. Consequently, Plan East became void. On September 17, following the Molotov-Ribbentrop Pact, the Soviets broke the Soviet-Polish Non-Aggression Pact by invading Poland. The Red Army met little resistance, as the Polish Army was concentrated in the West, fighting the Germans. Thus, the Soviets managed to occupy Polish Kresy in short order.