Free City of Danzig

The Free City of Danzig (German: Freie Stadt Danzig; Polish: Wolne Miasto Gdańsk) was a city-state under the protection and oversight of the League of Nations between 1920 and 1939, consisting of the Baltic Sea port of Danzig (now Gdańsk, Poland) and nearly 200 other small localities in the surrounding areas. The country was established on 15 November 1920, per the terms of Article 100 (Section XI of Part III) of the 1919 Treaty of Versailles, following the end of World War I.

Although predominantly German-populated, the territory was bound by the imposed union with Poland, which covered foreign policy, defense, customs, railways, and post, and remained distinct from both the post-war Weimar Republic and the newly independent Polish Republic. Additionally, Poland was granted certain rights related to port facilities in the city.

In the 1920 Constituent Assembly election, the Polish Party received over 6% of the vote; however, its percentage of votes later declined to approximately 3%. A large number of Danzig Poles voted for the Catholic Centre Party instead. In 1921, Poland began developing the city of Gdynia, a mid-sized fishing town. This new port, located north of Danzig, was established on territory awarded in 1919, known as the Polish Corridor. By 1933, the commerce passing through Gdynia exceeded that of Danzig. By 1936, the city's Senate had a majority of local Nazis, and agitation to rejoin Germany was stepped up.

After the German invasion of Poland in 1939, the Nazis abolished the Free City and incorporated the area into the newly formed Reichsgau of Danzig-West Prussia. The Nazis classified the Poles and Jews living in the city as subhumans, subjecting them to discrimination, forced labor, and extermination at Nazi concentration camps, including nearby Stutthof (now Sztutowo, Poland). Upon the city's capture in the early months of 1945 by the Soviet and Polish troops, a significant number of German inhabitants perished in ill-prepared and over-delayed attempts to evacuate by sea, while the remainder fled or were expelled. The city was fully integrated into Poland due to the Potsdam Agreement, while members of the pre-war Polish ethnic minority began returning, and new Polish settlers started arriving. Gdańsk suffered severe underpopulation due to these events and did not recover until the late 1950s.