Polish-Soviet war

In the Polish-Soviet war 1919-1921 military force proved the determinant of Poland's frontiers in the east, a theater rendered chaotic by the repercussions of the Russian revolutions and civil war.

Pilsudski envisioned a new federation with Lithuania and Polish domination of western Ukraine, centered at Kiev, forming a Polish-led East European confederation to block Russian imperialism.

Lenin, leader of the new communist government of Russia, saw Poland as the bridge over which communism would pass into the labor class of a disorganized postwar Germany.

Fighting started in 1919, when Polish self-organised military units in an area known as Kresy (Belarus, Western Ukraine and Lithuania) started quarrelling with local communist units and bolsheviks attacking from east. Eventually Polish forces took over whole area.

When Pilsudski carried out a military thrust into Ukraine in 1920 after a deal made with Petlura, he was met by a Red Army counterattack that drove into Polish territory almost to Warsaw. Although many observers marked Poland for extinction and Bolshevization, Pilsudski halted the Soviet advance before Warsaw and resumed the offensive. The Poles were not able to exploit their new advantage fully, however; and the Soviets were more eager to sign a peace treaty. The Soviets offered the Polish delegation as much territory as they wanted; the Poles preferred to sign a compromise Peace of Riga in early 1921 that split the disputed territory in Belorussia and Ukraine between Poland and Soviet Russia. However, Poland agreed on sovietisation of Belarus and Ukraine.

The treaty avoided ceding historically Polish territory back to the Russians. Nevertheless, numerous Polish minority in Soviet Union, that at first was given 2 national Polish Soviet Republic, were subsequently deported to Kasakhstan 1934-1938, around 400 000 died from hunger. (see also genocide)