The Kingdom of Poland, also known informally as the Regency Kingdom of Poland (Polish: Królestwo Regencyjne), was a client or puppet state of Germany created during World War I. This government was recognized by the emperors of Germany and Austria-Hungary in November 1916, and it adopted a constitution in 1917. The decision to create a state of Poland was taken by Germany in order to attempt to legitimise its military occupation amongst the Polish inhabitants, following upon German propaganda sent to Polish inhabitants in 1915 that German soldiers were arriving as liberators to free Poland from subjugation by Russia.
The state was utilised by the German government alongside punitive threats to induce Polish landowners living in the German-occupied Baltic territories to move to the state and sell their Baltic property to Germans in exchange for moving to Poland, and efforts were made to induce similar emigration of Poles from Prussia to the state.
Following the armistice with Germany that ended World War I, the area became part of the Second Polish Republic.
The Second Polish Republic, also known as the Second Commonwealth of Poland or the interwar Poland, refers to the country of Poland between the First and Second World Wars (1918–1939). Officially known as the Republic of Poland or the Commonwealth of Poland (Polish: Rzeczpospolita Polska), the Polish state was recreated in 1918, in the aftermath of World War I. When, after several regional conflicts, the borders of the state were fixed in 1922, Poland's neighbours were Czechoslovakia, Germany, the Free City of Danzig, Lithuania, Latvia, Romania and the Soviet Union. It had access to the Baltic Sea via a short strip of coastline either side of the city of Gdynia. Between March and August 1939, Poland also shared a border with the then-Hungarian province of Carpathian Ruthenia. Despite internal and external pressures, it continued to exist until 1939, when Poland was invaded by Nazi Germany, the Soviet Union and the Slovak Republic, marking the beginning of World War II in Europe. The Second Republic was significantly different in territory to the current Polish state. It used to include substantially more territory in the east and less in the west.
Poland maintained a slow but steady level of economic development. The cultural hubs of interwar Poland - Warsaw, Kraków, Poznań, Wilno and Lwów - became major European cities and the sites of internationally acclaimed universities and other institutions of higher education. By 1939, the Republic had become "one of Europe's major powers".