The Adriatic Campaign of World War I was a naval campaign fought during World War I between the Austro-Hungarian Navy, and the Mediterranean squadrons of the United Kingdom, France, and the Kingdom of Italy.
It consisted mainly of Austro-Hungarian coastal bombardments of Italy's Adriatic coast, and wider-ranging German/Hungarian submarine warfare into the Mediterranean.
Allied forces mainly limited themselves to blockading the German/Hungarian navies in the Adriatic, which was successful in regards to surface units, but failed for the U-boats, which found safe harbours and easy passage into and out of the area for the whole of the war. Considered a relatively secundary part of the naval warfare of World War I, it nonetheless tied down significant forces.
The Adriatic campaign is important even because were used in war for the first time successfully new weapons, like the human torpedo of Raffaele Rossetti and the MAS of Luigi Rizzo. These small navy vessels sank two Austrian battleships in 1918, the SMS Viribus Unitis and the SMS Szent István.
On 6 August 1914 an Anglo-French naval agreement was signed, giving France the leadership of naval operations in the Mediterranean. The remaining British Mediterranean forces, one armored cruiser, four light cruisers, and sixteen destroyers were placed under the control of the French Mediterranean Fleet and both Gibraltar and Malta would be open as bases to the French.
One day after the French declaration of war against Austria-Hungary on 11 August the French fleet under Admiral Augustin Boué de Lapeyrère entered Malta. He had orders to sail with all available French and British ships, pass into the Adriatic Sea and undertake whatever operation he thought best against an Austrian port. Lapeyrère decided to surprise the Austrian vessels enforcing a blockade of Montenegro. The main Allied force comprised the French battleships Courbet, Jean Bart, and the cruiser Julien De La Graviere. Two French squadrons of pre-dreadnoughts, two squadrons of cruisers, and 5 destroyer squadrons were held back in support. The British support group comprised two armored cruisers and three destroyer divisions. The Anglo-French force succeeded in cutting off and sinking the Austro-Hungarian light cruiser SMS Zenta off Bar on 16 August.
Throughout most of late August most of the action was simple bombardment of Serbian and Montenegrin troops by Austrian ships. On August 9 the pre-dreadnought Monarch shelled the French radio station at Budva, while the destroyer Panther shelled Mount Lovcen. On August 17 Monarch shelled a Montenegrin radio station off Bar, then another station off Volovica Point on August 19. Meanwhile a French squadron shelled Austrian troops on Prevlaka.
Both the French and the Austrians spent much of this time laying extensive minefields throughout the shallow waters of the Adriatic. Mostly this was done by destroyers, and at night. Several steamships ran afoul of these mines and either sunk or were damaged.
In July the German battlecruiser Goeben sailed to Triest from Pola. She and the German cruiser Breslau had been anchored there since the beginning of the summer. On August 1 Goeben and Breslau rendezvoused at Brindisi, then headed for Messina to take on coal. They left for Constantinople on August 6, shadowed by British cruiser Gloucester.
On August 7 the Austro-Hungarian Fleet (6 battleships, 2 cruisers, 19 destroyers and torpedo boats) sortied from Pola to escort Goeben and Breslau through Austro-Hungarian territorial waters, returned to port following day without ever making contact. Goeben and Breslau briefly engaged Gloucester and the chase was abandoned by the British. By August 10 both German warships were safely in the Dardanelles and heading for Turkey.
In November the French submarine Cugnot managed to slip into the Bocche di Cattaro as far as Topla Bay but was chased out by the Austrian destroyer SMS Blitz, and the torpedo boat Tb 57T. Later that month the French submarine Curie raided the harbor barrage of Pola to wait for her chance to intrude. Two days later, on 20 December, during an attempt to sneak into the harbour she got entangled in an anti-submarine net and could not free herself. Forced to surface for fresh air, she was sunk by the Austrian destroyer Magnet and Tb 63T, with three casualties. The Austrians raised the wreck between December 1914 and February 1915. It was then repaired and commissioned as U 14 in June 1915.
In February the French destroyer Dague, while escorting the transport Whitehead to Bar was sunk after hitting a mine. Also that month the Austrian submarine U-12 was unsuccessfully attacked off Cape Mendra by a French submarine. Austrian destroyer Csikós shelled Montenegrin positions at Bar with Tb 15 and Tb 68F.
In April the Austrian U-5 (commanded by Lt. Georg Ritter von Trapp) chased the French armored cruiser Victor Hugo off Paxos, but was unable to fire any torpedoes. The U-5 also torpedoed the French armored cruiser Léon Gambetta after a two-day chase off Santa Maria di Leuca, causing 684 fatalities including Rear-Admiral Sénès. Only 137 French sailors survived. The Austrian U-4 torpedoed and damaged the British light cruiser HMS Dublin. Also the Austrian destroyer Warasdiner shelled enemy positions at Bar.
When Italy declared war against Austria-Hungary on May 23 the Austrian fleet was quick to act, launching several attacks on the Marche region of Italy. That day the destroyer Dinara and Tb 53T bombarded the port of Ancona. The destroyer Lika, on reconnaissance duty between Palagruža and Cape Gargano, shelled the semaphore and radio station at Vieste and fired upon the Italian destroyer Turbine. On May 24 the bulk of the Austrian fleet at Pola sailed for the Italian Adriatic coast. This included the dreadnoughts Viribus Unitis, Tegetthoff, Prinz Eugen, and eight pre-dreadnoughts. The fleet bombarded several cities and other targets in and around the Province of Ancona, especially damaging the port town of Ancona itself.
The destroyer Velebit shelled the Italian airship Città di Ferrara off Ancona. The pre-dreadnought Radetzky and two torpedo boats bombarded Potenza Picena, then returned to Pola. The Radetzky-class pre-dreadnought Zrinyi, with two torpedo boats bombarded Senigallia, destroying a train and damaging a railway station and a bridge, then returned to Pola. The torpedo boat Tb 3 was unsuccessfully bombed by an Italian airship. The light cruiser Admiral Spaun shelled the Italian signal station at Cretaccio Island, while Sankt Georg, with two torpedo boats, shelled Rimini, damaging a freight train. The destroyer Streiter shelled the signal station near Torre di Mileto. The light cruiser Novara, a destroyer and two torpedo boats entered Corsini Channel and shelled an Italian torpedo boat station, a semaphore station, and coastal artillery batteries.
The light cruiser Helgoland, aided by four destroyers sank the Italian destroyer Turbine in a pitched battle south of Pelagosa. The destroyer Tatra shelled the railway embankment near Manfredonia while the destroyer Csepel shelled the Manfredonia railway station.
In response, on 5 June, four different Allied task forces attacked the Austrian coast. Four Italian armoured cruisers, escorted by four French destroyers, shelled Cavtat; the British cruiser HMS Dublin escorted by five Italian destroyers shelled Donzella; the Italian light cruiser Quarto escorted by four destroyers bombarded Lastovo; The Italian light cruiser Nino Bixio, two Italian and two French destroyers shelled the island of Lissa. On June 9 a mixed force of British, French and Italian destroyers shelled the Austro-Hungarian signal station at Cape Rondini in Albania.
The armoured cruiser Sankt Georg and a squadron of torpedo boats bombard Rimini on June 16, causing minor damage. Then on June 17 the cruisers Novara, Admiral Spaun and their escorts attack and sink the Italian steamer Maria Grazia off Giulianova. The next day they shelled Rimini and Fano, destroying the Italian signal station there.
The summer of 1915 was a successful time for Austrian submarines as well. On June 10 the U-11 sank the Italian submarine Medusa and torpedo boat Serpente. U-10 sank the Italian torpedo boat PN 5 on June 26 off Venice. The U-4 torpedoed and sank the Italian armoured cruiser Giuseppe Garibaldi on July 18. And U-5' captured the Greek steamer Cefalonia off Durazzo on August 29. But this was not without losses. On August 13 the U-3 was sunk at Brindisi by the French Destroyer Bisson, after having been severely damaged by the Italian auxiliary cruiser Città di Catania the day before.
The Austro-Hungarian naval air-arm also began regular bombing raids against Bari and Brindisi in June, slightly damaging the British protected cruiser Amethyst in one such raid with machine gun fire. And the British armed trawler Schiehallion was sunk by a mine. The Italian armoured cruiser Amalfi was sunk off Venice by the German UB-14 on July 2. While the Italian scout cruiser Marsala shelled Gravosa station on July 18, the Italian scout cruiser Quarto and three Italian destroyers attacked the Austrian installation at Guiparra.
Helgoland, seven destroyers and four torpedo boats supported the Austrian landings at Pelagosa on July 28 but within two weeks the battalion of troops are taken off. On August 17 the cruiser was unsuccessfully torpedoed by an Italian submarine on return journey. The town's freshwater cistern was damaged during the bombardment and the Italian troop evacuation took place the following day. The last act of the summer was the sinking on September 26 of the Italian battleship Benedetto Brin in Brindisi Harbor by Italian-speaking Austro-Hungarian saboteurs. Over 450 were killed.
In early December the French submarine Fresnel ran aground off the Bojana River estuary due to bad navigation, and was sunk by the Austrian destroyer Warasdiner. The Helgoland and three destroyers sortie against the Otranto Barrage from December 5 through December 22 and reconnaissance off the Albanian coast and San Giovanni di Medua. They sink an Italian picket boat, three steamships loaded with ammunition and two armed schooners en route to Northern Albania.
On December 30 the French submarine Monge is rammed by the Austrian cruiser Helgoland, and finally sunk by gunfire from the destroyer Balaton.
Austrian submarines sank or damaged a number of ships in 1916. U-11 captured the Italian hospital ship King Albert on January 18 at San Giovanni di Medua. U-6 sank the French destroyer Renaudin on March 16 at Durazzo. On June 8 U-5 torpedoed and sank the Italian troop transport Principe Umberto at Linguetta. Later U-5 fought a French-Italian destroyer group to a stalemate on August 2, and torpedoed the Italian Q-Ship Pantelleria south of Taranto on August 14.
On September 15, 1916 the two Austro-Hungarian seaplanes L.132 (Konjovics, Sewera) and L.135 (Zelezny, Klimburg) force by bombing the French sub Foucault (Dévin) to surface. L.135 finally sinks the sub while the 27 survivors were clinging to the two planes now floating, to be finally saved by the alarmed Tb 100M. This was the first sinking of a submarine by airplanes in naval war history.
The very same day the French sub Ampére (Dévin) scores two torpedo hits on the Austro-Hungarian Hospital ship No I (the former Lloyd steamer Elektra) off Cape Planka [Rat Ploca] causing two fatalities. The damaged hospital ship had to be beached in Borovica Bay for further repairs.
During night of December 22/23., 1916 Austro-Hungarian destroyers Scharfschuetze, Reka, Dinara and Velebit attacked the drifters patrolling the Otranto barrage, which applied for help to the French destroyers Casque, Protet, Commandant-RIVIÈRE, Commandant-Bory, Dehorter and Boutefeu which were escorting a convoy from Brindisi to Taranto. Because of communication problems only Casque and Commandant-RIVIÈRE attacked, but Caque's boiler rooms were hit immediately and she had to slow down to 23 knots (43 km/h). For further assistance the Italians ABBA, Nievo and Pilo left Brindisi shortly followed by the British cruiser Gloucester escorted by Impavido and Irriquieto. The French and the Italian groups met during darkness, ABBA rammed Casque, some moments later Boutefeu rammed ABBA. While the damaged vessels had to be taken into tow the Austrians escaped in the darkness.
The return from the Otranto battle, May 15, 1917, brought the British cruiser Dartmouth within the range of the German sub UC 25 which had already laid mines off Brindisi.
At 13.30 UC 25 torpedoed Dartmouth approximately thirty-six miles off Brindisi, for some time the ship was considered to be lost, but was manned by a rescue crew later and finally towed into port. On hearing that Dartmouth had been torpedoed, the Boutefeu went to assist, only to hit one of UC 25's mines.
By August 1917 Lt. Von Trapp and U-14 had sunk more than 24,000 tons of enemy shipping, including the Italian steamer Milazzo (11,480 t). The U-5 torpedoed the French cruiser Italia near Taranto on May 30, and on November 16 U-43 severely damaged the Italian steamer Oriona between Brindisi and Valona.
At 3.30 a.m. on the morning of June 10, 1918, the battleship Szent István in the company of SMS Tegetthoff and seven other ships en route to attack the Otranto Barrage, was hit by two torpedoes launched from the Italian MAS-15 Motor Torpedo Boat under Corvette Captain Luigi Rizzo near Premuda island, near Zara. Many of the 1087 crew were asleep, getting rested for the battle expected in a few hours. Immediate chaos soon changed into frantic efforts to save the vessel which was rapidly shipping water. Even the Tegetthoff was hit by another torpedo from a second MAS, but it did not exploded.
Then the Tegetthoff, which had at first sped away from the vicinity of the torpedo attack, returned and took the Szent István in tow, in an attempt to reach the massive dry dock at Pola. However the pumps were unequal to the task before them and the ship continued to slowly list, sinking at 6.12 a.m.
It is said she sank easily due to faults in the Tegetthoff class design: relatively low displacement and high centre of gravity, together with the tremendous weight of 12 × 305 mm main artillery. There were, however, only 89 dead, partly attributed to the fact that all sailors with the KuK had to learn to swim before entering active service.
The attack on the Otranto Barrage was cancelled as a consequence of this attack.
On 13 February 1918 the submarine Bernoulli (Audry) is lost with all hands after hitting a mine off the Bocche di Cattaro.
On 22/23 April 1918 the Austro-Hungarian Tátra-class destroyers Triglav, Uzsok, Dukla, Lika and Csepel encountered the British destroyers Jackal and Hornet, the Australian Torrens and the French Cimeterre. Hornet was badly damaged in the ensuing fight but the alarm went up and the Austrians turned for home, pursued by Jackal, who had lost her mainmast.
On 20 September 1918 the submarine Cirçé (Viaud) is torpedoed 7 nm north west of Cape Rodoni [Sqepi i Skenderbeut, Albania], by the Austro-Hungarian submarine U 47 (Seyffertitz) and lost with all hands.
On 1 November, the ex-Austro-Hungarian dreadnought SMS Viribus Unitis was sunk (with the merchant ship "Wien") at anchor at Pula by limpet mine attached by the crew (Rossetti and Paolucci) of an Italian mignatta (human torpedo). The mignatta was the precursor of the human torpedo and was invented by Major of naval engineers Raffaele Rossetti.
The whole Austrian navy was just being transferred to the new state (State of Slovenes, Croats and Serbs) after the dissolution of Austria Hungary.
Austro-Hungarian and many German U-boats operated out of the Adriatic for the whole of the war. Due to lack of cooperation of the Allies in the Mediterranean control zones, and the late institution of the convoy system, U-boats experienced substantial success throughout the first war years.