Poland's eastern border was determined by war. Poland seized Vilnius from Lithuania and part of Teschen from Czechoslovakia. After Marshal Pilsudski's forces drove the Red Army back from the gates of Warsaw in August 1920, Poland ended up with large sections of Belorussia and the Ukraine under the March 18, 1921 Treaty of Riga. More than 30 percent of the population of post-World War I Poland was ethnically non-Polish, Jews, Lithuanians, Belorussians, Ukrainians, Ruthenians and Germans (Crampton 41).
According to Roberts, both Germany and Russia had "open or suspected designs on territory Poland had acquired from them" (583). It, therefore, became a first axiom of Polish foreign policy to resist revision to the Versailles Treaty and to rely for enforcement of the Versailles settlement on the League of Nations, Poland's 1921 alliances with France and Rumania and, above all, on Poland's own fierce determination to remain independent of pressures from its more populous and powerful neighbors.
For a number of reasons, however, the Polish Second Republic was a weak state. Economically, it had been devastated by wars. Its economy, largely agricultural, was basically dependent on markets in more developed European nations which themselves were quite volatile in the 1920s. The Polish and German economies complimented each other, but after 1924 German-Polish trade trickled to a standstill as a result of tariff wars. Poland also experienced a somewhat less potent version of Germany's hyperinflation in 1923 and balance of payments problems. Curtis described the Polish parliamentary system in the years 1921-1926 as "unstable and erratic" (31). Poland had 13 changes of government during that period (Korbel 100). No one political party could achieve a stable majority in the legislature, the Sejm. Corruption was rife. Disgusted with the state of Polish politics, Pilsudski withdrew from political life in 1923. After his coup, he established an...