SMS Triglav

The Kingdom of Italy signed a secret treaty in London in late April 1915 breaking its alliance with the German Empire and Austro-Hungary and promising to declare war on the Central Powers within a month. Austro-Hungarian intelligence discovered this and Admiral Anton Haus, commander of the Austro-Hungarian Navy, planned a massive surprise attack on Italian ports and facilities on the Northern Adriatic coast, outside of interception range of the modern ships of the Regia Marina stationed at Taranto. During the bombardment, Triglav screened the ships involved.[7]

On 28 July, all six Tátra-class ships and the scout cruisers SMS Saida and SMS Helgoland, reinforced by the German submarine UB-14, attempted to recapture Pelagosa which had been occupied by the Italians on 11 July. Despite a heavy bombardment by the ships, the 108-man landing party was unable to overcome the 90-man garrison and was forced to withdraw.[8]

The Bulgarian declaration of war on Serbia on 14 October cut the existing supply line from Serbia to Salonika, Greece, and forced the Allies to begin supplying Serbia through ports in Albania. This took about a month to work out the details and the Austro-Hungarians took just about as long to decide on a response. Admiral Anton Haus, commander of the Austro-Hungarian Navy, ordered Linienschiffskapitän (Captain) Heinrich Seitz, Helgoland's commander, to take his ship, Saida and all six Tátra-class destroyers on a reconnaissance mission off the Albanian coast on the night of 22/23 November. They encountered and sank a small cargo ship and a motor schooner carrying flour for Serbia; four Italian destroyers were unable to intercept them before they reached friendly territory. Haus was initially reluctant to send his ships so far south, but an order from the Armeeoberkommando (High Command) on 29 November to patrol the Albanian coast and to disrupt Allied troop movements caused him to transfer Helgoland, her sister SMS Novara and the Tátra-class ships to Cattaro. On 6 December, Helgoland and the Tátras swept down the coast to Durazzo, sinking five motor schooners, including two in Durazzo harbor.[9]

Austro-Hungarian aircraft spotted a pair of Italian destroyers in Durazzo harbor on 28 December and Haus dispatched Seitz to take Helgoland, Triglav and her sisters SMS Csepel, SMS Lika, SMS Tátra and SMS Balaton south and search the area between Durazzo and Brindisi for them. If they were not found he was to arrive at Durazzo at dawn and destroy any ships found there. Seitz's ships sailed later that day and sank the French submarine Monge at 02:35. He was unable to find the destroyers and dutifully arrived off Durazzo at dawn. At 07:30 he ordered four of his destroyers into the harbor to sink the cargo ship and two schooners anchored there while Helgoland engaged the coastal artillery defending the port. A well-camouflaged 75-millimeter (3 in) artillery battery opened fire at 08:00 at point-blank range. While maneuvering to avoid its fire, Triglav and Lika entered a minefield. After striking two mines in quick succession, Lika sank at 08:03 and Triglav was crippled when her boiler rooms flooded after hitting one mine.[Note 2] After she was maneuvered out of the minefield, Csepel attempted to pass a towline, but it got tangled in one of her propellers, badly damaging it. Tátra was finally successful in securing a tow at 09:30, but was limited to a speed of six knots (11 km/h; 6.9 mph) when Seitz led his ships northwards. He radioed for assistance at 10:35 and was informed an hour later that the armored cruiser SMS Kaiser Karl VI and four torpedo boats were en route to support him.[10]

Italian observers had spotted Seitz's ships at 07:00 and the Allied quick-reaction force of the British light cruiser HMS Dartmouth and the Italian scout cruiser Quarto, escorted by five French destroyers, sortied in an attempt to cut off the Austro-Hungarian ships from their base at Cattaro. These were followed two hours later by the Italian scout cruiser Nino Bixio, the British light cruiser HMS Weymouth and four Italian destroyers. Seitz had ordered Triglav's crew taken off before any of the columns of smoke from these ships were spotted by his ships and he ordered Tátra to drop her tow at 13:15 and abandon Triglav. Five minutes later the Austro-Hungarian ships were spotted and the French destroyers were ordered to deal with Triglav at 13:38 while the cruisers pursued Seitz's ships. The French commander was deceived by smoke coming from Triglav's funnels and opened fire at 5,000 meters (5,500 yd). He was surprised when there was no return fire and decided to sink her with gunfire rather than expending torpedoes. This took over half-an-hour and left his ships well out of position for the pursuit of the other Austro-Hungarian ships.[11]