British cargo ship Danubian visited the Black Sea according to a letter of the German naval attaché at Istanbul dated3 February 1940

In his letter dated Istanbul, Turkey 3 February 1940 No. 712 g. reported the German naval attaché to the Oberkommando der Wehrmacht Abteilung Ausland the neutral ships passing Istanbul coming out of the Black Sea and loaded with contraband for or chartered by the enemy. An item reported on 28 January the British cargo ship Danubian loaded with 310 wagons board underway fro Constanta, Romania towards Alexandria, Egypt.

Source

Bundesarchiv. German Marineattaché for , Greece, Romania and Bulgaria 1939-1941. RM 12-II/459.