Six U-boats reached the Black Sea after a transport over land and canals [1] and operated from the harbours of Constanţa and Feodosiya[2] from 1942 to 1944.

In the First World War, Imperial German submarines had been transported via rail to the Pola Flotilla based in the Adriatic.

With Turkey as an ally of the Central Powers, the Imperial German Navy could also access the Black Sea via the Dardanelles and the Bosphorus, where the Constantinople Flotilla was based.

It was decided that small vessels, torpedo boats and U-boats, should be transported from the German Bight via the Danube to the Black Sea.

Six U-boats of the rather small coastal submarine Type IIB, which at the time served as training vessels in the Baltic Sea, were assigned to this flotilla in being.