Gdańsk is the Polish name for the major port known as Danzig in German. Located on the Baltic Sea, it formed part of Prussia and Germany until 1919. As a result of the Treaty of Versailles Danzig, although having a majority German population, was taken from Germany and created a 'Free City' in order to provide the newly-independent Poland with a sea port not controlled by Germany. In the late 1930s Danzig developed a strong Nazi movement, and control of the city, and of the "Polish Corridor" (Polish land separating Danzig and East Prussia from the rest of Germany) was used by Germany as an excuse for its aggressive posture towards Poland. The first shots of the Second World War in Europe were fired in Danzig, as German warships attacked a Polish garrison in the port. Following the defeat of Poland, Danzig was reincorporated into the Reich, but on Germany's defeat in 1945 it was ceded to Poland. Danzig was known for its shipyards, and here in 1980 Lech Walesa founded the Solidarity trade union that was within a decade to precipitate the collapse of Communism in Poland, later Central Europe and all the rest of the Eastern Bloc (the Balkans and the Soviet Union).