The Polish question was the issue, in international politics, of the existence of Poland as an independent state. Raised soon after the partitions of Poland in the late 18th century, it became a question current in European and American diplomacy throughout the 19th and parts of the 20th centuries. Historian Norman Davies notes that the Polish question is the primary lens through which most histories of Europe discuss the history of Poland, and was one of the most common topics of European politics for close to two centuries. The Polish question was a major topic at all major European peace conferences: at the Congress of Vienna in 1815, at the Versailles Conference in 1919, and at the Yalta Conference and the Potsdam Conference in 1945. As Piotr Wandycz writes, "What to the Poles was the Polish cause, to the outside world was the Polish question."

The Second Polish Republic, at the time officially known as the Republic of Poland, was a country in Central and Eastern Europe that existed between 7 October 1918 and 6 October 1939. The state was established in the final stage of World War I. The Second Republic ceased to exist in 1939, after Poland was invaded by Nazi Germany, the Soviet Union, and the Slovak Republic, marking the beginning of the European theatre of the Second World War. The Polish government-in-exile was established in Paris and later London after the fall of France in 1940.