Protection measures by the Entente for merchant shipping on the Ionian Sea 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 the shipping routes Messina-Cerigo, Messina-Maria di Leuca and Cerigo-Fanõ were protected by patrolling pairs of torpedo boats and submarine chasers.

In the Strait of Otranto was a group of steam fishing vessels fitted out with towing equipment and 'Flieger' [aircraft?] active and which in the morning and evenly suddenly appeared coming out of the sun. East of Malta were heavily escorted convoys sighted with in the front mostly small empy steamships followed by 4-5 loaded ships. Positive points for attacking were available around 90 nautical miles east of Malta.

Source

Bundesarchiv RM-40-622