250t-class torpedo boat

The 250t-class were high seas torpedo boats built for the Austro-Hungarian Navy in 1913–1916. A total of 27 boats were built by three shipbuilding companies, with the letter after the boat number indicating the manufacturer. There were small variations between manufacturers, mainly in the steam turbines used, and whether they had one or two funnels. The eight boats of the T-group were built by Stabilimento Tecnico Triestino, located at Trieste, designated 74 T – 81 T. The sixteen boats of the F-group were built by Ganz & Danubius at their shipyards at Fiume and Porto Re, designated 82 F – 97 F. The three M-group boats were manufactured by Cantiere Navale Triestino at Monfalcone, designated 98 M – 100 M.

All 27 boats saw service in World War I, performing convoy, escort and minesweeping tasks, and anti-submarine operations, but none were lost. In 1917, one of the 66 mm guns on each boat was placed on an anti-aircraft mount. Under the terms of the Treaty of Saint-Germain-en-Laye, the boats were transferred to various countries, including seven to Romania, six to Portugal, six to Greece, and eight to the newly created Kingdom of Serbs, Croats and Slovenes (later Yugoslavia). By 1940, thirteen boats of the class had been lost or scrapped, including all six Portuguese boats.

During World War II, the five remaining Greek boats were sunk by German aircraft during the Axis invasion of that country in April 1941. The six surviving Yugoslav boats were captured by the Italians during the Axis invasion of Yugoslavia in April 1941, and were operated by the Regia Marina. Immediately following the Italian capitulation in September 1943, one ex-Yugoslav boat was sunk by German aircraft, another was scuttled by its Italian crew, and a third fell into Allied hands. The rest were seized by the Germans. Of these, two were handed over to the Navy of the Independent State of Croatia, one of which was destroyed by Royal Navy Motor Torpedo Boats in 1944. The other was transferred to the Yugoslav Navy after World War II and continued to serve until 1959, when she was taken out of service. Another was operated by the German Navy (Kriegsmarine) with a Croatian crew until she was sunk by Royal Air Force aircraft in 1945. The surviving Croatian boat was handed over to the Yugoslav Navy after the war, and served until 1963. The remaining Romanian boat performed escort tasks in the Black Sea before being taken over by the Soviet Navy, and serving in their Black Sea Fleet until the end of the war. It was finally scrapped in 1958.

Background
In 1910, the Austria-Hungary Naval Technical Committee initiated the design and development of a 275 t coastal torpedo boat, specifying that it should be capable of sustaining 30 kn for 10 hours. This specification was based an expectation that the Strait of Otranto, where the Adriatic Sea meets the Ionian Sea, would be blockaded by hostile forces during a future conflict. In such circumstances, there would be a need for a torpedo boat that could sail from the Austro-Hungarian Navy base at Cattaro to the Strait during darkness, locate and attack blockading ships and return to port before morning. Steam turbine power was selected for propulsion, as diesels with the necessary power were not available, and the Austro-Hungarian Navy did not have the practical experience to run turbo-electric boats.

Description and construction
Stabilimento Tecnico Triestino (STT) of Trieste was selected for the contract to build eight vessels, ahead of one other tenderer. Despite the specifications of the contract being very close to the requirements for the coastal torpedo boat, the STT boats were classified as sea-going. The STT boats used Parsons turbines. Another tender was requested for four more boats, but when Ganz & Danubius reduced their price by ten percent, a total of sixteen boats were ordered from them. These boats were powered by AEG-Curtiss turbines, and had two funnels rather than the single funnel of the STT boats. The third contract went to Cantiere Navale Triestino (CNT), who used Melms-Pfenniger turbines, and their boats also had two funnels. The boats of all three groups used steam generated by two Yarrow water-tube boilers, one of which burned fuel oil and the other coal.

When completed, all 27 boats were armed with two Škoda 66 mm L/30 guns, and four 450 mm torpedo tubes. Each vessel could carry 10–12 naval mines.

T-group
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, a beam of 5.7 m, and a normal draught of 1.5 m. While their designed displacement was 262 t, they displaced about 320 t fully loaded. The crew consisted of 39 officers and enlisted men. Their Parsons turbines were rated at 5000 shp with a maximum output of 6000 shp and designed to reach a top speed of 28 kn. They carried 18 t of coal and 24 t of fuel oil, which gave them a range of 980 nmi at 16 kn.

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

F-group
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, a beam of 5.8 m, and a normal draught of 1.5 m. While their designed displacement was 266 t, they displaced about 330 t fully loaded. The crew consisted of 38 officers and enlisted men. Their AEG-Curtiss turbines were rated at 5000 shp with a maximum output of 6000 shp, and the boats were designed to reach a top speed of 28 kn. During trials, 93 F produced 6450 shp, and reached a top speed of 29.7 kn. They carried 20 LT of coal and 34 LT of fuel oil, which gave them a range of 1200 nmi at 16 kn. 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.

M-group
The M-group were built by CNT at Monfalcone between March 1914 and March 1916. They had a waterline length of 60.5 m, a beam of 5.6 m, and a normal draught of 1.5 m. While their designed displacement was 270 t, they displaced about 330 t fully loaded. The crew consisted of 38 officers and enlisted men. Their Melms-Pfenniger turbines were rated at 5000 shp with a maximum output of 6000 shp, and the boats were designed to reach a top speed of 28.5 kn. They carried enough coal and fuel oil to give them a range of 1200 nmi at 16 kn.

World War I
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. All 27 boats saw service, performing convoy, escort and minesweeping tasks, and anti-submarine operations. 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. In 1917, one of the 66 mm guns on each boat was placed on an anti-aircraft mount.

In late September 1917, 98 M was part of a squadron of four destroyers and four torpedo boats 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 led by Sparviero that had been sent to support an Italian air raid on Pola. In the resultant 45 minute melee, several Austro-Hungarian destroyers were damaged. As the squadron retreated through the minefields off Parenzo, 98 M was hit by Italian fire, resulting in one casualty. In June 1918, 76 T was part of the escort force that failed to protect the Austro-Hungarian dreadnought SMS Szent István from the Italian motor torpedo boats that sank her.

Elements of the Austro-Hungarian fleet mutinied in Cattaro in February 1918, 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. In October 1918, 87 F was at Durazzo in Albania 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.

Post-World War I transfers
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:

World War II
By 1940, thirteen boats of the class had been lost or scrapped, including all six Portuguese boats. At the time of the Axis Balkan Campaign of April 1941, T1 and T3 were assigned to the Southern Sector of Coastal Defence Command based at the Bay of Kotor, along with a number of minesweepers and other craft. T5–T8 comprised the 3rd Torpedo Division located at Šibenik. 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. 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. All six Yugoslav boats still in service were captured by the Italians during the German-led Axis invasion of Yugoslavia.

The five surviving Greek boats were all sunk by aircraft during the Axis invasion of Greece, also in April 1941. The first was Proussa, which was sunk off Corfu on 4 April by Italian Junkers Ju 87 "Picchiatello"s of the 239th Squadron, 97th Dive Bomber Group. Later, Kios was sunk off Athens on 22 April, Kyzikos at Salamis on 24 April, Pergamos off Salamis on 25 April, and Kidoniai south of the Peloponnese peninsula on the following day.

The three Romanian boats were initially deployed against the Soviet Navy Black Sea Fleet with the launching of Operation Barbarossa in June 1941, with Naluca and Sborul allocated to the 3rd Section of the Romanian Navy. On 9 July 1941, Naluca, along with a gunboat and three Motor Torpedo Boats (MTBs), sank the Soviet submarine SC-206 off the southern Romanian coast near Mangalia. Between 7–16 October 1941, all three Romanian torpedo boats were part of the escort for a minelaying group that laid several minefields along the Bulgarian coast to protect Axis shipping. Naluca was sunk by Soviet aircraft at Constanța on 20 August 1944, but Sborul and Smeul survived World War II, 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.

The Yugoslav boats served with the Royal Italian Navy (Regia Marina) under their Yugoslav designations. T3 and T5 were fitted with two 76 mm L/30 anti-aircraft guns in place of their 66 mm guns, but no other significant alterations were made to them. When the Italians capitulated in September 1943, the Germans seized T1 and transferred her to the Navy of the Independent State of Croatia. She was renamed Golešnica and continued in Croatian service until the end of the war. T3 was seized by the Germans at Rijeka and was renamed TA48. During her time in German service she was crewed exclusively by Croatian officers and sailors, and her complement was increased to 52. The Germans fitted her with two single 20 mm anti-aircraft guns. She was sunk in the port of Trieste by the Royal Air Force on 20 February 1945. T5 was returned to the Royal Yugoslav navy in exile in December 1943. T6 was scuttled by the Italians at Rimini on 11 September to avoid her falling into German hands. 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 the Yugoslav Partisans, and were preparing to mutiny when the Germans intervened. She was sunk by Royal Navy MTBs off Murter Island on 25 June 1944. T8 was sunk by German aircraft while under Italian control on 10 September 1944.

Post-World War II
Only four of the original twenty-seven 250t-class torpedo boats survived World War II, two in Yugoslav service and two in Soviet service. Golešnica was transferred to the Yugoslav Navy after the war. She was re-armed with two 40 mm guns on single mounts and four 20 mm guns, and her torpedo tubes were removed. She continued in Yugoslav service under that name until October 1959, when she was taken out of service. T5 was also transferred to the Yugoslav Navy after the war, and renamed Cer, she was fitted with two 40 mm guns on single mounts and one 20 mm gun. She served until 1962, when she was broken up. Musson and Toros were returned to Romania in October 1945, and stricken the following month.