250t-class torpedo boat

The T-group were built by STT at the Port of Trieste between April 1913 and December 1914. They had a waterline length of 58.2 m (190 ft 11 in), a beam of 5.7 m (18 ft 8 in), and a normal draught of 1.5 m (4 ft 11 in). While their designed displacement was 262 tonnes (258 long tons), they displaced about 320 tonnes (310 long tons) fully loaded. The crew consisted of 39 officers and enlisted men. Their Parsons turbines were rated at 5,000 shp (3,700 kW) with a maximum output of 6,000 shp (4,500 kW) and the boats were designed to reach a top speed of 28 knots (52 km/h; 32 mph).[2] They carried 18 tonnes (17.7 long tons) of coal and 24 tonnes (23.6 long tons) of fuel oil,[6] which gave them a range of 980 nmi (1,810 km; 1,130 mi) at 16 knots (30 km/h; 18 mph).[2]

The T-group boats were originally to be armed with three 66 mm (2.6 in) L/30 guns, and three 450 mm (17.7 in) torpedo tubes,[1] but this was changed to two guns and four torpedo tubes before the first boat was completed,[2] to standardise the armament with the following F-group. In 1914, one 8 mm (0.31 in) machine gun was added.[1]

When 74 T's turbines were initially installed, the problems with them were so significant that all her power and propulsion machinery had to be rebuilt. She was launched for a second time on 26 June 1914.[2]

The F-group were built by Ganz & Danubius at Fiume and nearby Porto Re between October 1913 and December 1916. They had a waterline length of 58.5 m (191 ft 11 in), a beam of 5.8 m (19 ft 0 in), and a normal draught of 1.5 m (4 ft 11 in). While their designed displacement was 266 tonnes (262 long tons), they displaced about 330 tonnes (320 long tons) fully loaded.[2] The crew consisted of 38 officers and enlisted men. Their AEG-Curtiss turbines were rated at 5,000 shp (3,700 kW) with a maximum output of 6,000 shp (4,500 kW), and the boats were designed to reach a top speed of 28 knots (52 km/h; 32 mph). During trials, 93 F produced 6,450 shp (4,810 kW), and reached a top speed of 29.7 knots (55.0 km/h; 34.2 mph). They carried 20 long tons (20.3 t) of coal and 34 long tons (34.5 t) of fuel oil,[6] which gave them a range of 1,200 nmi (2,200 km; 1,400 mi) at 16 knots (30 km/h; 18 mph).[7]

The F-group boat 86 F alongside the battleship SMS Erzherzog Franz Ferdinand

When Italy declared war on Austria-Hungary in May 1915, five incomplete F-group boats were towed to be completed in safety. 82 F, 83 F and 84 F were taken from Porto Re to Pola, and 90 F and 91 F were taken to Novigrad. This resulted in delays to the completion of these boats.[7]

The M-group were built by CNT at Monfalcone between March 1914 and March 1916. They had a waterline length of 60.5 m (198 ft 6 in), a beam of 5.6 m (18 ft 4 in), and a normal draught of 1.5 m (4 ft 11 in). Their designed displacement was 270 tonnes (266 long tons), and they displaced about 330 tonnes (320 long tons) fully loaded. The crew consisted of 38 officers and enlisted men. Their Melms-Pfenniger turbines were rated at 5,000 shp (3,700 kW) with a maximum output of 6,000 shp (4,500 kW), and the boats were designed to reach a top speed of 28.5 knots (52.8 km/h; 32.8 mph). They carried enough coal and fuel oil to give them a range of 1,200 nmi (2,200 km; 1,400 mi) at 16 knots (30 km/h; 18 mph).[3]

At the outbreak of World War I, 74 T – 77 T comprised the 1st Torpedo Group of the 3rd Torpedo Craft Division of the Austro-Hungarian 1st Torpedo Craft Flotilla.[8] All 27 boats saw service, performing convoy, escort and minesweeping tasks, anti-submarine operations,[1] and shore bombardment missions.[9] They also conducted patrols and supported seaplane raids against the Italian coast. Due to inadequate funding, the 250t class were essentially coastal vessels, despite the original intention that they would be used for "high seas" operations.[10] On 24 May 1915, several 250t-class boats were involved in the shelling of various Italian shore-based targets known as the Bombardment of Ancona. 74 T – 77 T were part of the operation against Ancona, and 78 T – 81 T were involved in the shelling of Porto Corsini near Ravenna.[11] In the latter action, an Italian 120 mm (4.7 in) shore battery returned fire, hitting the light cruiser Novara and damaging 80 T.[12] On 23 July, 74 T and 78 T participated in a shore bombardment and landing operation led by the scout cruiser Saida against San Benedetto del Tronto, Ortona and Termoli on the central Adriatic coast of Italy.[13] In late November 1915, the Austro-Hungarian fleet deployed a force from its main fleet base at Pola to Cattaro in the southern Adriatic; this force included six of the T-group torpedo boats. This force was tasked to maintain a permanent patrol of the Albanian coastline and interdict any troop transports crossing from Italy.[14]

On 3 February 1916, 83 F, 87 F and 88 F were involved in another shore bombardment operation against Ortona and San Vito Chietino, this time led by the armoured cruiser Sankt Georg.[13] Three days later, the scout cruiser Helgoland, 74 T, 78 T, 80 T, 83 F, 87 F and 88 F were intercepted by the British light cruiser HMS Weymouth and French destroyer Bouclier north of Durazzo in Albania, during which the only damage was caused by a collision between 74 T and 83 F. On 3 May, 76 T, 92 F, 93 F and 98 M – 100 M were accompanying four destroyers when they were involved in a surface action off Porto Corsini against an Italian force led by the flotilla leaders Cesare Rossarol and Guglielmo Pepe. On this occasion the Austro-Hungarian force retreated behind a minefield with no damage to the torpedo boats, and only splinter damage to the Huszár-class destroyer Csikós. On 24 May, an Austro-Hungarian force that included 75 T, 89 F, 92 F, 98 M – 100 M and four destroyers was involved in a brief surface action with two Italian torpedo boats off Chioggia in the northern Adriatic. During the action, 75 T was hit.[15] On the night of 31 May – 1 June 1916, the Tátra-class destroyers Orjen and Balaton, accompanied by 77 T, 79 T and 81 T, raided the Otranto Barrage, the Allied naval blockade of the Strait of Otranto. Orjen sank one drifter, but once the alarm had been raised, the Austro-Hungarian force withdrew.[16]

On 9 July, Novara led a force which included 87 F and two Kaiman-class torpedo boats in another night raid on the Otranto Barrage which resulted in the sinking of two drifters.[15] On 2 August, the Huszár-class destroyers Warasdiner and Wildfang were returning from a shore bombardment of Molfetta on the southern Adriatic coast of Italy when they were engaged by an Allied force which included the Italian cruiser Nino Bixio and the British cruiser HMS Liverpool. The cruiser Aspern, 80 T and 85 F were sent to assist the two destroyers, but action was broken off before the opposing cruisers got within range. Nine days later, 91 F, 94 F and 98 M were chased and engaged by Italian torpedo boats off Pola, resulting in splinter damage to one of the Italian boats. On 4 November, three Italian destroyers and three torpedo boats were involved in a brief encounter in the northern Adriatic with two Austro-Hungarian destroyers accompanied by 83 F, 87 F and 88 F. The following day, the same three torpedo boats conducted a shore bombardment of Sant'Elpidio a Mare.[9]

Pola

Cattaro

Strait of Otranto

Cortellazzo

Senigallia

Cesenatico

Map of the Adriatic Sea showing the location of major ports and actions

During 1917, one of the 66 mm (2.6 in) guns on each boat was placed on an anti-aircraft mount.[4] On 21 April, four Austro-Hungarian destroyers, accompanied by 84 F, 92 F, 94 F and 100 M, conducted a night raid on the Otranto Barrage, sinking one drifter.[17] On 11 May, the British submarine H1 stalked 78 T off Pola, firing two torpedoes at her. The British captain had kept his submarine's periscope extended too far and for too long, and the tell-tale "feather" alerted the crew of 78 T, allowing her to avoid the incoming torpedoes.[18] That night, the destroyer Csikós, accompanied by 78 T, 93 F and 96 F, were pursued in the northern Adriatic by an Italian force of five destroyers, but were able to retire to safety behind a minefield.[17] On 14–15 May 1917, several 250t-class boats were part of the support forces for a major raid on the Otranto Barrage. When the raiding force departed, torpedo boats and aircraft secured the approaches to the Austro-Hungarian naval base at Cattaro. Once the raiding force had departed for the barrage, Sankt Georg, a destroyer, and 84 F, 88 F, 99 M and 100 M were to be prepared to sortie out to support the raiders on their return voyage. The old coastal defence ship Budapest and 86 F, 91 F and 95 F were also available at Cattaro if needed. Although the raid was a success, sinking 14 drifters, the raiding force was then engaged by Allied ships in the Battle of the Otranto Straits. Both support groups sailed to meet the returning Austro-Hungarian force, including the heavily damaged Novara, which was under tow. On marrying-up with the raiding force, the torpedo boats fanned out to screen the larger warships, protecting them as they returned to port.[17][19][20]

On 3 June, the destroyers Wildfang and Csikós, along with 93 F and 96 F, briefly encountered three Italian MAS boats off the mouth of the Tagliamento river in the far north of the Adriatic. On 23 September, 77 T and 78 T were laying a minefield off Grado in the northern Adriatic when they had a brief encounter with an Italian MAS boat.[17] The following night, 94 F and three other torpedo boats again had a short and inconclusive engagement with Italian torpedo boats in the northern Adriatic.[17] On 29 September, 90 F, 94 F and 98 M were accompanying a squadron of four destroyers supporting an air attack on the Italian airfield at Ferrara by flying boats. After destroying an Italian airship, the squadron withdrew at high speed in the darkness, but was intercepted by an Italian squadron of eight destroyers that had been sent to support an Italian air raid on Pola. In the resultant 45 minute chase towards Parenzo, two Italian destroyers and three Austro-Hungarian destroyers were damaged, and 94 F was hit by splinters. As the squadron retreated through the minefields off Parenzo, 98 M was also hit by Italian fire, resulting in one casualty.[17][21]

On 14 November, 84 F, 92 F, 94 M, 99 M and 100 M encountered four Italian destroyers off the mouth of the Piave, but the torpedo boats were again able to elude their pursuers by sailing behind a minefield. Two days later, the coastal defence ships Wien and Budapest sailed to engage a 152 mm (6.0 in) Italian shore battery at Cortellazzo near the mouth of the Piave, with an escort that included 84 F, 92 F, 94 F, 98 M – 100 M and some minesweepers. Both Wien and Budapest were hit, but none of the torpedo boats suffered any damage. After an Italian force of seven destroyers and three MAS boats appeared, the bombarding force withdrew.[17] On 28 November, 250t-class boats were involved in two shore bombardment missions. In the first mission, 79 T, 86 F and 90 F supported the bombardment of Senigallia by three destroyers, before they were joined by 78 T, 82 F, 87 F, 89 F and 95 F and another three destroyers for the bombardment of Porto Corsini, Marotta and Cesenatico. On 19 December, a large Austro-Hungarian force engaged the Italian shore battery at Cortellazzo. The force consisted of the pre-dreadnought battleship Árpád, the light cruiser Admiral Spaun, Budapest, six destroyers, ten torpedo boats including 84 F, 92 F, 94 F and 98 M – 100 M, and ten minesweepers. None of the ships of the bombarding force suffered damage during the mission.[22]

Elements of the Austro-Hungarian fleet mutinied in Cattaro in February 1918,[23] and in May, a plot was discovered to take over 80 T at Pola. The motive appeared to be nationalism. Two of the ringleaders, a Czech and a Dalmatian Croat, were tried, convicted and executed by firing squad.[24][25][26] On 13 May, the destroyer Dukla, 84 F and 98 M were at Durazzo when two Italian MAS boats forced the harbour, sinking one Austro-Hungarian freighter.[22] On 10 June, 76 T – 79 T, 81 T and 87 F were part of the escort force that failed to protect the Austro-Hungarian dreadnought Szent István from the Italian MAS boats that sank her. During that action, 76 T fired at the Italian boats, but did not score a hit.[27][28] On 1 July, the destroyers Balaton and Csikós, along with 83 F and 88 F, were chased offshore from Caorle by seven Italian destroyers. All four Austro-Hungarian ships were hit, with 83 F hit three times, and 88 F struck once. One of the Italian destroyers was hit three times, and another was slightly damaged by splinters. On 6 September, 86 F and two other torpedo boats were engaged by three Italian destroyers in the Gulf of Drin. 86 F was hit, and the Austro-Hungarian force withdrew.[29] On 2 October, 87 F was at Durazzo when the port was bombarded by a multinational Allied naval force. She escaped with minor damage, in what was the last major action involving the Austro-Hungarian Navy.[29][30]

Under the provisions of the Treaty of Saint-Germain-en-Laye, all Austro-Hungarian warships were surrendered to the Allies. The 250t-class torpedo boats were distributed among Romania, Portugal, Greece, and the newly created Kingdom of Serbs, Croats and Slovenes (later Yugoslavia), as follows:[4]

Transfer of T-group torpedo boats[2]

Austro-Hungarian name	Transferred to	New name	Inter-war fate
74 T	Romanian Navy	Viforul	scrapped in 1932
75 T	Romanian Navy	Vartejul	scrapped in 1932
76 T	Navy of the Kingdom of Serbs, Croats and Slovenes	T1	—
77 T	Navy of the Kingdom of Serbs, Croats and Slovenes	T2	scrapped in 1939
78 T	Navy of the Kingdom of Serbs, Croats and Slovenes	T3	—
79 T	Navy of the Kingdom of Serbs, Croats and Slovenes	T4	lost 1932[lower-alpha 2]
80 T	Romanian Navy	Vijelia	scrapped in 1932
81 T	Romanian Navy	Sborul	—

Transfer of F-group torpedo boats[7]

Austro-Hungarian name	Transferred to	New name	Inter-war fate
82 F	Romanian Navy	Năluca	—
83 F	Romanian Navy	Smeul	—
84 F	Romanian Navy	Fulgerul	lost in the Bosphorus[lower-alpha 3]
85 F	Portuguese Navy	Zezere	lost 1921[lower-alpha 4]
86 F	Portuguese Navy	Ave	scrapped 1940
87 F	Navy of the Kingdom of Serbs, Croats and Slovenes	T5	—
88 F	Portuguese Navy	Cavado	lost 1921[lower-alpha 5]
89 F	Portuguese Navy	Sado	scrapped 1940
90 F	Portuguese Navy	Liz	scrapped 1934
91 F	Portuguese Navy	Mondego	scrapped 1938
92 F	Hellenic Navy	Proussa	—
93 F	Navy of the Kingdom of Serbs, Croats and Slovenes	T6	—
94 F	Hellenic Navy	Panormos	lost 1938[lower-alpha 6]
95 F	Hellenic Navy	Pergamos	—
96 F	Navy of the Kingdom of Serbs, Croats and Slovenes	T7	—
97 F	Navy of the Kingdom of Serbs, Croats and Slovenes	T8	—

Transfer of M-group torpedo boats[3]

Austro-Hungarian name	Transferred to	New name	Inter-war fate
98 M	Hellenic Navy	Kyzikos	—
99 M	Hellenic Navy	Kios	—
100 M	Hellenic Navy	Kydoniai	—

The Yugoslav torpedo boat T3 photographed in 1931

By 1940, thirteen boats of the class had been lost or scrapped, including all six Portuguese boats.[4] At the time of the Axis invasion of Yugoslavia in April 1941, the Yugoslav boats T1 and T3 were assigned to the Southern Sector of Coastal Defence Command based at the Bay of Kotor, along with several minesweepers and other craft.[31] T5–T8 comprised the 3rd Torpedo Division located at Šibenik.[32] On 8 April, the four boats of the 3rd Torpedo Division, along with other vessels, were tasked to support an attack on the Italian enclave of Zadar on the Dalmatia coast. They were subjected to three Italian air attacks and, after the last one, sailed from the area of Zaton into Lake Prokljan, where they remained until 11 April.[33] On 12 April, the 3rd Torpedo Division arrived at Milna on the island of Brač, and refused to follow orders to sail to the Bay of Kotor.[34] All six Yugoslav boats were then captured by the Italians.[35]

The five surviving Greek boats were all sunk by aircraft during the German invasion of Greece, also in April 1941. The first was Proussa, which was sunk off Corfu on 4 April by Italian Junkers Ju 87 "Picchiatellos" of the 239th Squadron, 97th Dive Bomber Group.[36][lower-alpha 7] Later, Kios was sunk off Athens on 22 April, Kyzikos at Salamis on 24 April, Pergamos off Salamis on 25 April, and Kydoniai south of the Peloponnese peninsula on the following day, all by German aircraft.[3]

The three Romanian boats were initially deployed against the Soviet Navy Black Sea Fleet following the launch of Operation Barbarossa in June 1941.[4] Năluca took part in the sinking of one Soviet submarine near Mangalia on 9 July 1941,[37][38][39] but was herself sunk by Soviet aircraft at Constanța on 20 August 1944. Sborul and Smeul survived World War II,[35] having been transferred to the Soviet Black Sea Fleet in late August 1944 after Romania changed sides and joined the Allies, serving as Musson and Toros respectively.[40]

The Yugoslav boats served in a coastal and second-line escort role with the Royal Italian Navy (Italian: Regia Marina) in the Adriatic under their Yugoslav designations, and were fitted with two 76 mm (3.0 in) L/30 anti-aircraft guns in place of their 66 mm guns,[41] but no other significant alterations were made to them.[42] After the Italians capitulated in September 1943, they transferred T1 back to the KJRM-in-exile in December of that year.[lower-alpha 8] T3 was seized by the Germans at Rijeka on 16 September 1943 and was renamed TA48. She was commissioned on 15 August 1944, and was used for patrol and escort work in the northern Adriatic.[45] The Germans added to her armament, fitting her with two single 20 mm (0.79 in) anti-aircraft guns in addition to the guns fitted by the Italians, and removing two of her torpedo tubes.[46] There are two versions of how TA48 was employed. The first version indicates that she was crewed exclusively by Croatian officers and sailors, but remained under German control,[1] and the second states that she was handed over to the Navy of the Independent State of Croatia, but was repossessed by the Germans on 14 December 1944 because they considered the Croatians unreliable.[45] Her complement was also increased to 52 during her German-Croatian service.[1] She was sunk in the port of Trieste by Allied aircraft on 20 February 1945.[1][43][lower-alpha 9]

T5 was also returned to the KJRM-in-exile in December 1943.[1] T6 was scuttled by the Italians 30 km (19 mi) north of Rimini on 11 September as she had insufficient fuel on board to reach an Allied port.[49] Once under German control, T7 was also handed over to the Navy of the Independent State of Croatia, and served under her Yugoslav designation. Her crew came under the influence of Yugoslav Partisan propaganda, and were preparing to mutiny when the Germans intervened.[1][43] On 24 June 1944, she and the S-boats S 154 and S 157 of the 7th S-Boat Flotilla were sailing between Šibenik and Rijeka, protecting German sea supply routes along the Adriatic, when they were attacked by the Royal Navy Fairmile D motor torpedo boats MTB 659, MTB 662 and MTB 670 near the island of Kukuljari, south of Murter Island. The MTBs fired two torpedoes at T7, but missed, so they closed and engaged her with their guns, setting her ablaze. She was beached, and 21 crew were rescued by the MTBs. The British crews later examined the wreck, capturing five more crew, then destroyed her with demolition charges.[50] T8 was sunk 37 km (23 mi) north-west of Dubrovnik by German aircraft while evacuating Italian troops from Dalmatia on 10 or 11 September 1943.[1][43][44][49]

Only four of the twenty-seven 250t-class torpedo boats survived World War II, two in Yugoslav service and two in Soviet service. T1 was commissioned by the Yugoslav Navy after the war as Golešnica.[43] She was re-armed with two 40 mm (1.6 in) guns on single mounts and four 20 mm (0.79 in) guns, and her torpedo tubes were removed. She continued in Yugoslav service under that name until October 1959. T5 was also commissioned by the Yugoslav Navy after the war,[43] and renamed Cer. 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, when she was broken up.[51] Musson and Toros were returned to Romania in October 1945, and stricken the following month.[52][lower-alpha 10]