British surveillance forces using Gulf of Saros for refuelling and shelter according to a letter of the German naval attaché at Istanbul dated 2 December 1939

In his letter dated Istanbul, Turkey 2 December 1939 No. 491 g. reported the German naval attaché to the Oberkommando der Wehrmacht Abteilung Ausland that the British surveillance forces used the Gulf of Saros or Saros Bay [north of Istanbul] for refuelling and shelter for bad weather.

Source

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