History of Poland
The Polish People's Republic ("Polska Rzeczpospolita Ludowa") was established under the rule of the communist Polish United Workers' Party (PZPR). The name change from the Polish Republic was not officially adopted, however, until the proclamation of the Constitution of the Polish People's Republic in 1952.
Second Polish Republic
After more than a century of Partitions between the Austrian, the Prussian, and the Russian imperial powers, Poland re-emerged as a sovereign state at the end of the First World War in Europe in 1917-1918. The victorious Allies of World War I confirmed the rebirth of Poland in the Treaty of Versailles of June 1919. It was one of the great stories of the 1919 Paris Peace Conference. Poland solidified its independence in a series of border wars fought by the newly formed Polish Army from 1918 to 1921. The extent of the eastern half of the interwar territory of Poland was settled diplomatically in 1922 and internationally recognized by the League of Nations.