Yugoslav torpedo boat T5

The original concept of operation for the 250t-class boats was that they would sail in a flotilla at the rear of a cruising battle formation, and were to intervene in fighting only if the battleships around which the formation was established were disabled, or in order to attack damaged enemy battleships.[10] When a torpedo attack was ordered, it was to be led by a scout cruiser, supported by two destroyers to repel any enemy torpedo boats. A group of four to six torpedo boats would deliver the attack under the direction of the flotilla commander.[11] During World War I, 87 F was used for convoy, patrol, escort and minesweeping tasks, anti-submarine operations,[1] and shore bombardment missions.[7][12] On 9 December 1915, 87 F, two other 250t-class boats, two Kaiman-class torpedo boats and three destroyers accompanied the protected cruiser Szigetvár to escort Austro-Hungarian seaplanes attacking Ancona. Five days later, Szigetvár led a similar seaplane raid on Rimini, escorted by two destroyers, two Kaiman-class boats, and three 250t-class boats including 87 F.[13]

On 2 February 1916, 87 F, two other 250t-class boats, and the Huszár-class destroyer Wildfang were sent from the main Austro-Hungarian naval base at Pola to the Bocche escorting the armoured cruiser Sankt Georg and the scout cruiser Helgoland.[14] The following day this group of vessels conducted a shore bombardment operation against the Italian coast near San Vito Chietino, including the railway line between Ortona and Tollo.[12] During this operation, Sankt Georg exchanged fire with an Italian armed train operated by the Royal Italian Navy (Italian: Regia Marina), equipped with 4.7 in (12 cm) guns.[14] Three days later, Helgoland, 87 F and five other 250t-class boats were sent to intercept the British light cruiser HMS Liverpool and Italian Rosolino Pilo-class destroyer Pilade Bronzetti which had attacked Wildfang while she was escorting a seaplane raid.[14] Instead of meeting the pair that had forced Wildfang to retreat, the Austro-Hungarian force encountered the British light cruiser HMS Weymouth and French Bouclier-class destroyer Bouclier – which had since relieved them – north of Durazzo in Albania.[15] The torpedo boats manoeuvred into two groups of three for the attack, but in one of the groups two leading boats collided, with one sustaining damage, forcing that group to retreat to the port of Budva in Austro-Hungarian-occupied Montenegro, and the other group pressed their attack unsuccessfully. The entire Austro-Hungarian force then returned to the Bocche, having lost an opportunity to interdict significant convoy traffic further south between Albania and Italy.[14]

On 3 July 1916, Helgoland led an unproductive raid on the Otranto Barrage, the Allied naval blockade of the Strait of Otranto, escorted by three destroyers, 87 F, and two other 250t-class boats.[16] On the night of 8/9 July, the scout cruiser Novara led 87 F and two Kaiman-class boats in a more successful raid on the barrage which resulted in the sinking of two drifters,[15] damage to two more, and the capture of nine crew as prisoners of war. The force was chased by Italian destroyers, but escaped with the assistance of Austro-Hungarian seaplanes from the Bocche that attacked the Italian ships.[16] On 28 August, a large force led by Sankt Georg, the armoured cruiser Kaiser Karl VI, Novara and Helgoland, escorted by five destroyers, 87 F and three other 250t-class boats, steamed to the Italian coast in an attempt to draw Italian ships into a trap set with four Austro-Hungarian u-boats. The Italians did not detect the Austro-Hungarian ships due to fog, and the operation was a failure.[17] On the night of 4/5 October, 87 F and two other 250t-class boats steamed to the barrage but located no targets.[18] On 4 November 1916, three Italian destroyers and three torpedo boats were involved in a brief encounter in the northern Adriatic with two Austro-Hungarian destroyers accompanied by 87 F and two other 250t-class boats. The following day, the same three torpedo boats conducted a shore bombardment of Sant'Elpidio a Mare.[19]

In 1917, one of her 66 mm guns was placed on an anti-aircraft mount.[2] On 21 May 1917, the suffix of all Austro-Hungarian torpedo boats was removed, and thereafter they were referred to only by the numeral.[1] On 18 October, 87 and five of her 250t-class sisters joined three destroyers and three seaplanes in escorting three steamers towing 32 boats from Pola to Pirano to reinforce Austro-Hungarian forces on the Italian front ahead of the forthcoming Battle of Caporetto in which the Italian forces were routed.[20] Along with other 250t-class boats she escorted the scout cruiser Admiral Spaun in an attack on the harbour of Grado between Venice and Triest.[21] 87 and four other 250t-class boats were laying mines between Venice and Ancona on 19 November when they were intercepted by four Italian destroyers, but managed to escape.[22] On 28 November, a number of 250t-class boats were involved in two shore bombardment missions. In the second mission, 87 joined seven other 250t-class boats and six destroyers for the bombardment of Porto Corsini, Marotta and Cesenatico.[23]

On 4 February 1918, 87 and two of her sisters accompanied four destroyers on a mission supporting seaplanes attacking the air station at Venice.[24] By 1918, the Allies had strengthened their ongoing blockade on the Strait of Otranto, as foreseen by the Austro-Hungarian Navy. As a result, it was becoming more difficult for the German and Austro-Hungarian U-boats to get through the strait and into the Mediterranean Sea. In response to these blockades, the new commander of the Austro-Hungarian Navy, Konteradmiral Miklós Horthy, decided to launch an attack on the Allied defenders with battleships, scout cruisers, and destroyers.[25] During the night of 8 June, Horthy left Pola in the upper Adriatic with the dreadnought battleships Viribus Unitis and Prinz Eugen. At about 23:00 on 9 June 1918, after some difficulties getting the harbour defence barrage opened, the dreadnoughts Szent István and Tegetthoff,[26] escorted by one destroyer and six torpedo boats, including 87, also departed Pola and set course for Slano, north of Ragusa, to rendezvous with Horthy in preparation for a coordinated attack on the Otranto Barrage. About 03:15 on 10 June,[lower-alpha 2] while returning from an uneventful patrol off the Dalmatian coast, two Royal Italian Navy (Italian: Regia Marina) MAS boats, MAS 15 and MAS 21, spotted the smoke from the Austrian ships. Both boats successfully penetrated the escort screen and split to engage the dreadnoughts individually. MAS 21 attacked Tegetthoff, but her torpedoes missed.[28] Under the command of Luigi Rizzo, MAS 15 fired two torpedoes at 03:25, both of which hit Szent István. Both boats evaded pursuit. The torpedo hits on Szent István were abreast her boiler rooms, which flooded, knocking out power to the pumps. Szent István capsized less than three hours after being torpedoed.[27]

On 26 September 1918, 87 was one of four 250t-class boats that assisted two destroyers escorting three steamers when they were attacked off Cape Menders (current day Cape Mendra near Ulcinj, Montenegro) by the British submarine H1.[29] On 2 October, 87 was at Durazzo in Albania when the port was bombarded by a multinational Allied naval force. The only other Austro-Hungarian warships in port were two destroyers, and they were seriously outnumbered and outgunned by the Allied force, which included five cruisers and eight destroyers.[30] 87 escaped with minor damage when she was struck by a torpedo that failed to detonate,[21][31] in what was the last major action involving the Austro-Hungarian Navy.[31]

87 survived the war intact.[1] In 1920, under the terms of the previous year's Treaty of Saint-Germain-en-Laye by which rump Austria officially ended World War I, she was allocated to the Kingdom of Serbs, Croats and Slovenes (KSCS, later Yugoslavia). Along with three other 250t-class F-group boats, 93, 96 and 97, and four 250t-class T-group boats, she served with the Royal Yugoslav Navy (Serbo-Croatian Latin: Kraljevska Mornarica, KM; Краљевска Морнарица). Transferred in March 1921,[32] in KM service, 87 was renamed T5.[2] When the navy was formed, she and the other seven 250t-class boats were the only modern sea-going vessels in the KM.[33] During the French occupation of Cattaro, the original torpedo tubes were destroyed or damaged, and new ones of the same size were ordered from the Nejedil factory in Czechoslovakia.[6] In KM service it was intended to replace one or both guns on each boat of the 250t class with a longer Škoda 66 mm (2.6 in) L/45 gun, and it is believed that this included the forward gun on T5.[5] She was also fitted with two Zbrojovka 15 mm (0.59 in) machine guns.[6] In KM service, the crew increased to 52,[5] and she was commissioned in 1923.[34]

In 1925, exercises were conducted off the Dalmatian coast, involving the majority of the navy.[35] In May–June 1929, six of the eight 250t-class torpedo boats accompanied the light cruiser Dalmacija, the submarine tender Hvar and the submarines Hrabri and Nebojša, on a cruise to Malta, the Greek island of Corfu in the Ionian Sea, and Bizerte in the French protectorate of Tunisia. The ships and crews made a very good impression while visiting Malta.[36] In 1932, the British naval attaché reported that Yugoslav ships engaged in few exercises, manoeuvres or gunnery training due to reduced budgets.[37] By 1939, the maximum speed achieved by the 250t class in Yugoslav service had declined to 24 kn (44 km/h; 28 mph).[5]

In April 1941, Yugoslavia entered World War II when it was invaded by the German-led Axis powers. At the time of the invasion, T5 was assigned to the 3rd Torpedo Division located at Šibenik, which also included her sisters T3, T6 and T7. On the first day of the invasion, 6 April, they were anchored across the entrance of the St. Anthony Channel that links Šibenik Bay to the Adriatic, on a line between Jadrija on the northern side of the channel and Zablaće on the southern side, when aircraft of the Regia Aeronautica (Italian Royal Air Force) attacked Šibenik.[34] On the same day, Kapetan bojnog broda[lower-alpha 3] Ivan Kern arrived to take command of the division, and the four boats sailed up the channel towards Šibenik then north to Zaton where they were again attacked unsuccessfully by Italian bombers.[21] T3 incurred boiler damage and was sent south to Primošten for repairs to be undertaken.[34]

On 8 April more unsuccessful Italian air attacks on the three boats occurred, and the only effective anti-aircraft gun between them – the 40 mm (1.6 in) gun on T6 – malfunctioned. The three vessels then sailed east across Lake Prokljan to Skradin where the population begged them to leave the harbour to avoid the town being bombed by the Italians. Their request was rebuffed, and during an Italian bombing raid some of the boats along with the water carrier Perun were slightly damaged.[39] On the following morning, Italian aircraft attempted to sink Perun using aerial torpedoes, but all missed. In response, Kern ordered T6 to escort Perun to the Bay of Kotor, and the two vessels arrived there the next day without incident, where T6's malfunctioning gun was repaired and she was loaded with weapons, supplies and extra men and sent to Šibenik. On the return journey she stopped at Makarska and learned of the declaration of the creation of the Axis puppet fascist state, the Independent State of Croatia (NDH).[40] On the same day, the division, along with other vessels, were tasked to support an attack on the Italian enclave of Zara on the Dalmatian coast, which was quickly cancelled as soon as the establishment of the NDH was declared.[41][42] On the evening of 11 April, T6 met with T5 and the rest of the division near Šibenik. Kern ordered her to deliver her load to Šibenik then meet the rest of the division at Milna on the island of Brač, which she did on 12 April. Kern was unable to obtain orders from Šibenik Command by telephone, so took the Uskok-class torpedo boat Uskok to try to obtain some. His second-in-command was unable to maintain order, and a third of the crews deserted. When Kern returned, he gave orders to sail to the Bay of Kotor,[40] but the crews of the division refused to follow his orders.[43] He retrieved his personal gear from T7 and taking command of Uskok, sailed to the Bay of Kotor.[40] Eventually Kern fled into exile with other KM vessels.[44] On 13 April, the Orjen-class torpedo boat Triglav arrived with orders that the division should return to Šibenik to evacuate the staff of Šibenik Command. The first order was complied with, but upon arrival at Šibenik the boat crews were given the choice of returning to their homes or sailing to Split to join the NDH navy. The boats then sailed to nearby Divulje, to follow through on an intention to join NDH navy,[21] but all four boats of the division were then captured by the Italians.[45]

T5 was then operated by the Italians under her Yugoslav designation, conducting coastal, second-line escort, and anti-Partisan duties in the Adriatic. Her main guns were replaced by two 76 mm (3.0 in) L/40 anti-aircraft guns,[46] she was fitted with one or two Breda 20 mm (0.79 in) L/65 anti-aircraft guns,[47] and her bridge was enclosed,[3] but no other significant alterations were made to her,[48] although one pair of torpedo tubes may have also been removed.[4] According to Italian records, in February 1942, T5 and her sister T6 (ex-93 F then 93) chased an Allied submarine between Split and the island of Mulo near Primošten, but there is no record of this incident in British records.[21] On 8 October 1942, T5 was escorting the coastal steamship Guiseppe Magliulo when they were unsuccessfully attacked by the British submarine HMS Safari near Cape Planka.[49] On 28 December 1942, the Partisans established their first naval station at Podgora on the Dalmatian coast. From this base, the fledgling Partisan Navy attacked and captured five coastal steamships over the next few days. On 1 January 1943, T5, along with two captured Yugoslav Arbe-class minelayers, a patrol vessel and an armed tug, attacked Podgora from the sea, and an Italian landing party was put ashore. The Italian troops were repelled by the Partisan 4th Dalmatian Brigade. The operation was repeated three days later, with the addition of air support, but a planned second landing was cancelled.[50] On 12 February, T5 was escorting a convoy of four coastal steamers near Cape Planka when HMS Thunderbolt unsuccessfully attacked the group.[49]

About 18:00 on 10 September 1943, at the time of the Italian capitulation, T5, the sub-chaser Ernesto Giovannini, and several smaller vessels escaped from Split.[51] The commander of Maridalmazia (the maritime command of Dalmatia), Ammiraglio di divisione[lower-alpha 4] Antonio Bobbiese, along with his staff, escaped from Split on board a motor boat and when he arrived at the island of Susak off the northern Adriatic coast, he took overT5.[51] The boat reached the island of Lastovo west of Dubrovnik and on the evening of 13 September sailed in a convoy to Brindisi in Italy, docking there at midday the following day. Bobbiese was strongly reprimanded for leaving his command prematurely.[52] T5 was sent to Malta and returned to the KM-in-exile on 7 December, but was not considered operational and thus survived the war.[1][53]

T5 was commissioned as a coastal patrol vessel by the new Yugoslav Navy after the war, renamed Cer and allocated the hull number PBR-92.[53][54] She was fitted with two 40 mm (1.6 in) guns on single mounts and one 20 mm (0.79 in) gun, and her torpedo tubes were also removed. She served until 1962,[55] and the following year she was stricken and towed to a scrapyard to be broken up.[53]