The Central Powers submarines in the Mediterranean during WWI

The German officers had good control on their crews and, like in Pula, the German sailors were separated from Austro-Hungarian sailors and lived in much better conditions. Some days after the mutiny started, the German submarines (along with the Austro-Hungarian land forces) helped the Austro-Hungarian authorities against rebel-sailors. During the mutiny, the Austro-Hungarian leadership in Kotor sent following message: "It is necessary to take all measures to make impossible for the fleet to escape (to Italy). It is better to sink the fleet. And because of that, in the last case, German submarines must be called."

Conclusion

There were many battlefields around the Mediterranean Sea in the WWI. Balkan, Italy, Turkey (Dardanelles), Palestine (of that time) etc. It was vital for the Allies to ensure safe maritime traffic to and around all the battlefields. Also, the Allies had important maritime traffic lines through the Mediterranean Sea. For example, France had colonies on the Northern African coast. So, they had also colonial troops in those countries and they had to transport them to the Western front (in France). Great Britain had to transport troops from the Far East and from Australia to the France and Great Britain (via the Suez Canal). Also, they had to transport troops from Egypt to Gallipoli (within the Dardanelles’ operation) and lately to Balkan. In 1918 British transported their troops frequently from the Mediterranean war theatre to the Western front (France). Because of all mentioned Germans sent their submarines in the Mediterranean. But, they send the submarines not just to obstruct and to endanger the Allies’ maritime transport but also to make an impact on other members of the Central Powers, Austria-Hungary, Turkey and Bulgaria. Austro-Hungarian submarines operated mainly in the Adriatic Sea and successfully limited operations of the Allies’ big warships in the Adriatic Sea. German submarines operated in the Mediterranean Sea (against the Allies’ maritime transport) and in the Aegean Sea and the Black Sea (within the Dardanelles’ operation). The German submarines were based in Pula, Kotor and Istanbul. German submarines that operated against the Imperial Russian Navy warships (in the Black Sea) were stationed in Bulgarian harbours Burgas and Varna.

The German submarines, which served in the Mediterranean Sea, could to base in just few ports. In Turkey, possible submarine bases were just in Istanbul and in Turkish ports in the Black Sea. But, the allied naval forces in the front of Dardanelles blocked those submarines (and German/Turkish surface ships). Turkish coast in the Mediterranean Sea is long but the Turkish Navy was weak and wasn’t able to ensure safety of the Turkish (Mediterranean) coast from the Allies’ naval attack. Because of reasons mentioned above there were just two safe bases for the German submarines which operated in the Mediterranean Sea, Pula (the Northern Adriatic) and Kotor (the Southern Adriatic). Another problem for the German submarines in the Mediterranean was that there was just one shipyard in which they could be repaired completely. It was the Austro-Hungarian Navy shipyard in Pula. The shipyard in Pula was good equipped and had qualified engineers and workers. During the war workers from Germany were also sent to work on the submarines in the shipyard in Pula.

In order to stop German and Austro-Hungarian submarines’ penetration from the Adriatic into the Mediterranean and their return in the Adriatic, the Allies organised the Otranto barrage. Otranto is placed between the Adriatic and the Ionian Sea, line from Italy to Albania. The British Royal Navy established the barrage on 26th September 1915 as a system of underwater barriers (fishing nets and anti submarine mines); observations by aeroplanes, patrolling by surface ships etc. In 1916 the French Navy and the Italian Navy joined into the barrage operations. In 1917 the US navy as well joined the barrage operations at Otranto. During the war the barrage was improved, but the barrage only made the penetration of German submarines from the Adriatic into the Mediterranean Sea more difficult. The barrage never completely stopped passing of the German submarines.

Germans submarines forced the Allies to change their strategy of naval warfare and marine traffic in the Mediterranean Sea. During the war the Allies had to organise convoys, which was more complicated and slower than ordinary maritime traffic. In 1916 British maritime traffic from Australia and from the Far East had to be directed around South Africa instead of through the Mediterranean Sea (via the Suez Canal). The Central Powers submarines in the Mediterranean Sea sank about 35 % of the whole Allied tonnage that was sunk during WWI.

On 27th May 1915 Italy joined the Entente. The joining changed the Central Powers strategy in the Mediterranean Sea. But the submarine warfare for Austro-Hungarian and German submarines became easier because from that moment almost all ships in areas of their operations (the Adriatic Sea, the Mediterranean Sea and the Aegean sea) were under enemies’ (i.e. the Allies’) flags. So, the Central Powers submarines hadn’t potential problems with neutral ships.

On 31st August 1916 and on 9th January 1917 there were two conferences in Germany about unrestricted submarine warfare. On the both conferences were present the Imperial Chancellor, Dr. Von Bethmann-Hollweg, and German military leadership. On the both conferences the military leadership reported that Germany is able just to keep situation of defence. Also, the leadership reported about successful blockade of Germany, by the Allies. Because of all above mentioned, the leadership asked for permission for unrestricted submarine warfare, from 1st February 1917. The situation was so bad for Germany, that they were ready even for involvement of the USA and other neutral countries in the war (on the Allies’ side, naturally). The Imperial Chancellor Dr. Von Bethmann-Hollweg said (on 9th January 1917): "The U-boat war is the last card."

German leaders knew importance of submarine warfare in the Mediterranean Sea. During the war one quarter of new-built submarines were sent to the Mediterranean Sea. Also, German submarines which operated in the Mediterranean Sea received their orders directly from the Naval Staff in Berlin and not from the Fleet. In spite of all that Germans simply hadn’t enough submarines to completely defeat the Allies naval forces and to completely interrupt the Allies’ maritime traffic.

On 3rd November 1918 the Italian Navy Command asked leadership of the former Austro-Hungarian Fleet in Pula about presence of German submarines in the Adriatic Sea. The Austro-Hungarian Navy and the Fleet was collapsed (as well as the whole Austro-Hungarian Empire) and Italians didn’t care about possible threat, but Germany was still in the war and German submarines could threaten Italian efforts to take control of the eastern Adriatic coast. The leadership from Pula answered that the German submarines had left the Adriatic Sea few days ago. After that, nothing could stop Italy to take control of Pula, the whole Istrian peninsula and some parts of the eastern Adriatic coast and islands. This event shows for the best influence of the German Navy Mediterranean Submarine Flotilla on the Central Powers war efforts in the Mediterranean Sea.

Just some details about the Central Powers’ submarine warfare were mentioned in this article. There were much more events. For example, the first submarine sank by aeroplanes was French submarine "Foucault" (397 t). The submarine was sank by the Austro-Hungarian Navy aeroplanes (hydroplanes) "L132" and "L135", on 15th September 1916.

During the war Italy lost two battleships because of Austro-Hungarian sabotages. Italian battleship "Benedetto Brin" (13400 t) sank in the port of Brindisi on 30th September 1915. Also, Italian battleship "Leonardo da Vinci" (23000 t) capsized in the port of Taranto on 2nd August 1916, because of explosion. How the saboteurs came on the places? It is most likely that they came by means of submarines.

In this article names of towns are given in two languages, Croatian and Italian languages- Pula (Pola), Rijeka (Fiume) and Kotor (Cattaro). This is because in books and other sources you can find one of the names, in Croatian or Italian version. Both versions are suitable and equal.