Final answer:
Danzig is the principal seaport of Poland and the birthplace of the Solidarity trade union, which played a crucial role in opposing Communist domination and led to the collapse of the Soviet Union's power.
Step-by-step explanation:
The city known as Danzig is the principal seaport of Poland and the birthplace of the Solidarity trade union, led by Lech Walesa.
The Solidarity movement started as an independent trade union in the 1980s and gained momentum for political change in Poland.
It was a key player in opposing Communist domination and eventually led to the collapse of the power of the Soviet Union and Communism in Eastern Europe.
Poland now has a democratic government and a thriving capitalist economy.