Allies Entente taken precautionary measures against enemy submarines according to the Kriegsnachrichten of the Chef des Admiralstabes der Marine dated Berlin 18 August 1917

An item referred to tidings received from patrolling submarines in the first half of August reporting that steamships at least were escorted by torpedo boats; the capes along the African north coast were only by night and outside 200 metres rounded . Off the capes were in the night guard vessels, and when it was time for the shipping traffic were the lights set. By day light were the ships lying in the harbors and when that was not possible were capes close to the coasline rounded. Steamships measured 3,000-4,000 tons. The steamships passing the North African coast used withut exception the La Galite Canal [Galite was a French Tunesian archipelago] keeping exactly in the 150 metres line. During the day were aircraft patrolling able to see enemy submarines. In the night was fire burning with/for correct identification. In the ‘free’water area were good positions in neutral stripes and north west Marittimo. There valuable heavily protected stamships coming from the Strait Messina passing apparently Sicily in the north.

Source

Bundesarchiv RM-40-622