Portia was one of eighteen Admiralty M-classdestroyers ordered by the British Admiralty in February 1915 as part of the Fifth War Construction Programme.[1] The M-class was an improved version of the earlier L-class destroyers, designed to reach a higher speed in order to counter rumoured German fast destroyers.[2]
The destroyer was 265 feet (80.8 m) long overall, with a beam of 26 ft 8 in (8.1 m) and a draught of 9 ft 3 in (2.8 m). displacement was 994 long tons (1,010 t) normal and 1,025 long tons (1,041 t) full load. Power was provided by three Yarrow boilers feeding two Brown-Curtissteam turbines rated at 25,000 shaft horsepower (19,000 kW) and driving two shafts, to give a design speed of 34 kn (63 km/h; 39 mph).[3] Three funnels were fitted. 296 long tons (301 t) of oil were carried, giving a design range of 3,450 nautical miles (6,390 km; 3,970 mi) at 15 kn (28 km/h; 17 mph).[4]
Armament consisted of three 4 in (102 mm) Mk IV QF guns on the ship's centreline, with one on the forecastle, one aft on a raised platform and one between the middle and aft funnels. A single 2-pounder (40 mm) pom-pom anti-aircraft gun was carried, while torpedo armament consisted of two twin mounts for 21 in (533 mm) torpedoes.[5]Portia had a complement of 76 officers and ratings.[4]
Portia was transferred from the Grand Fleet on 23 January 1917 and allocated to anti-submarine operations after the German navy declared unrestricted submarine warfare in February 1917.[9] On 14 February, the destroyer joined sister shipsPartridge, Plover and Rob Roy in hunting the submarineSM UC-44. The search did not find anything.[10] Also common were escort duties to protect convoys of merchant ships. Sometimes the operations did not deter the attackers, as on 17 May when the submarine SM U-19 attacked a seven-ship convoy which the destroyer was escorting and sank one, a Swedish vessel.[11] Others were more successful, such as Convoy HH13 of thirteen ships which came through without loss.[12]
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