European theatre of World War II
The Second Polish Republic, commonly known as Interwar Poland, refers to the country of Poland in the period between the two World Wars (1918–1939). Officially known as the Republic of Poland (), the Polish state was re-established in 1918, in the aftermath of World War I. The Second Republic ceased to exist in 1939, when Poland was invaded by Nazi Germany, the Soviet Union and the Slovak Republic, marking the beginning of the European theatre of World War II.