British tanker Eocene visit the Black Sea according to a letter of the German naval attaché at Istanbul dated 22 December 1939

In his letter dated Istanbul, 22 December 1939 No. 575g reported the German naval attaché to the Oberkommando der Wehrmacht Abteilung Ausland the steamships passing Istanbul, loaded with contraband for the enemy. An item reported on 18 December the unarmed British tanker Eocene loaded with 825 ton petrol bound for Haifa, Palestina and 4,815 ton petroleum.

Source

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