British merchant ships visiting the Black Sea often armed and with naval gunners on board according to a letter of the German naval attaché at Istanbul dated 3 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 that the guns on board of British merchant ships were regularly crewed with 4-6 active naval gunners. The ships mentioned in the last week were also fitted out with depth charges, mostly 6-8 ones.

Source

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