Danzig is an important port and old Hanseatic city on the Baltic Sea. In the Middle Ages it was regarded as the richest city in the world. This certainly was an exaggerated and above all Eurocentric view. It nevertheless shows the importance of the city and explains, why Danzig was the goal of many foreign invasions. Danzig faced several Polish and Danish attempts of conquest, later became a part of Prussia, and in 1918 became a free state. The free state of Danzig existed until 1939. That year it was dissolved and incorporated into the German Reich. Since the end of World War Two, Danzig is Polish. As a Free State, Danzig issued its own coins. From 1920 there are emergency coins of 10 pfennigs that were minted in the city's gun factory. The first regular coin series appeared in 1923. The unit of account was the gulden at 100 pfennigs.