Yugoslav torpedo boat T5

During World War I, 87 F was used for convoy, patrol, escort and minesweeping tasks, anti-submarine operations,[1] and shore bombardment missions.[4][6] On 3 February 1916, 87 F and two other 250t-class boats were involved in a shore bombardment operation against Ortona and San Vito Chietino, led by the armoured cruiser Sankt Georg.[6] Three days later, the scout cruiser Helgoland, 87 F and five other 250t-class boats 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 two of the other 250t-class boats. On 9 July, the scout cruiser Novara led a force which included 87 F and two Kaiman-class torpedo boats in a raid on the Otranto Barrage, the Allied naval blockade of the Strait of Otranto, which resulted in the sinking of two drifters.[7] 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 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.[8] In 1917, one of her 66 mm guns was placed on an anti-aircraft mount.[2] On 28 November 1917, a number of 250t-class boats were involved in two shore bombardment missions. In the second mission, 87 F joined seven other 250t-class boats and six destroyers for the bombardment of Porto Corsini, Marotta and Cesenatico.[9]

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.[10] During the night of 8 June, Horthy left the naval base of 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,[11] escorted by one destroyer and six torpedo boats, including 87 F, 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.[13] 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.[12] 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.[14]

87 F 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 F, 96 F and 97 F, and four 250t-class T-group boats, she served with the Royal Yugoslav Navy (Serbo-Croatian Latin: Kraljevska Jugoslovenska Ratna Mornarica, KJRM; Краљевска Југословенска Ратна Морнарица). Transferred in March 1921,[15] in KJRM service, 87 F was renamed T5.[2] In 1925, exercises were conducted off the Dalmatian coast, involving the majority of the navy.[16] 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. It is not clear if T5 was one of the torpedo boats involved. The ships and crews made a very good impression while visiting Malta.[17] In 1932, the British naval attaché reported that Yugoslav ships engaged in few exercises, manoeuvres or gunnery training due to reduced budgets.[18]

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 included her three former F-group sisters.[19] 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 Zara 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.[20] 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.[21] All four former F-group boats were then captured by the Italians.[22]

T5 was then operated by the Italians under her Yugoslav designation, conducting coastal and second-line escort duties in the Adriatic. Her guns were replaced by two 76 mm (3.0 in) L/40 anti-aircraft guns,[23] but no other significant alterations were made to her.[24] After the Italians capitulated in September 1943, she was returned to the KJRM-in-exile in December of that year.[1] T5 was commissioned by the Yugoslav Navy after the war,[25] 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.[26]