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.
Polish–Soviet War
With the success of the Greater Poland Uprising (1918–1919), Poland had re-established its statehood for the first time since the 1795 partition. Forming the Second Polish Republic, it proceeded to carve out its borders from the territories of its former partitioners. Many of these territories had long been the object of conflict between Russia and Poland.