'Exterminate' was a British naval undertaking to destroy three German warships (one torpedo boat and two corvettes in the Adriatic Sea (2/3 November 1944).
The action was fought in the Kvarner Gulf in the northern end of the Adriatic Sea, between the islands of Pag and Lussino (Losinj in Serbo-Croat) between two British destroyers and a German force of one old destroyer and two modern corvettes, which were escorting a convoy carrying men, equipment and supplies from Sibenik to Fiume (Rijeka). Themselves suffering no losses, the British ships sank all three German ships, which lost more than 200 men killed. The British ships recovered 90 other men, and an additional 20 German sailors were rescued two days later by German vessels sent to search for survivors. The convoy of 19 landing craft being escorted by the three German warships was not intercepted and reached its destination by 2 November.
After the Italian capitulation of 8 September 1943, on the day before the Allied 'Avalanche' landings at Salerno on the Italian mainland, the Yugoslav partisan forces had captured most of the Dalmatian east coast of the Adriatic Sea. The Germans made all haste to reoccupy these areas, and particularly the northern Adriatic ports of Trieste, Fiume and Pula, and on 10 September established the Operationszone Adriatisches Küstenland (Operational Zone of the Adriatic Littoral) with its headquarters in Trieste. As an Allied landing in the area was anticipated, the Operationszone Adriatisches Küstenland controlled a substantial German military strength including newly formed German naval units, many of whose vessels were Italian warships seized in 'Achse' (ii). As a consequence, an engagement with British warships was almost inevitable.
In the second half of 1944 the British deployed a flotilla of small warships in the Adriatic Sea, both to secure the area and to attack German coastal shipping. This latter became increasingly significant for the German forces deployed in the German puppet state of Croatia, and in particular Dalmatia, as the road and rail routes into and out of the area became unsafe because of the activities of the Yugoslav partisans. To deny the Germans use of the northern part of the Adriatic Sea, the British launched 'Exterminate' with the primary task of destroying German corvettes. On 26 October, the Yugoslav partisan forces informed Lieutenant Commander M. Morgan-Giles, commander of the coastal forces in the northern part of the Adriatic Sea, that there were two German destroyers in a cove on the south coast of Rab island.
The German 'Wikinger' withdrawal from the Dalmatian cities of Zadar and Sibenik to Fiume involved the movement of troops and matériel in two convoys protected by German warships. The withdrawal was a consequence of the inevitable and indeed imminent capture of Zadar and sibenik by the Yugoslav partisan forces. The 'Wikinger II' convoy. which departed Sibenik at 17.00 on 1 November, comprised four Marinefährprahme landing craft MFP 522, MFP 554, MFP 484 and MFP 354 as 'Gruppe 'A', and 13 Pionier-Landungsboote (combat engineer landing craft) and two large Sturmboot assault landing craft as Gruppe 'B'.
In the first part of their passage, the convoy was protected by the 2nd Gruppe of Kapitänleutnant Günther Schulz’s 3rd Schnellboots-Flottille, which then passed the responsibility to Korvettenkapitän Friedrch-Wilhelm Thorwest’s Fiume-based 2nd Geleit-Flottille (escort flotilla). The 3rd Schnellboots-Flottille initially comprised the 'E-boats' S 154, S 156 and S 158, but on 25 October a British air attack on Sibenik by de Havilland Mosquito warplanes sank S 158[/] and damaged S 156, leaving only one operational boat, S 154, for the convoy duty. At the time, the only operational vessels of the 2nd Geleit-Flottille were TA 20 (ex-Italian 'Urakaze' class destroyer Audace) with a crew of 113 men, UJ 202 and UJ 208 (ex-Italian 'Gabbiano' class corvettes Melpómene and Spingarda) each with a crew of about 110 men, and the fast minesweeper R 187. TA 20 was commanded by Oberleutnant Heinz Guhrke and , UJ 202 by Oberleutnant Heinz Trautwein and UJ 208 Oberleutnant Klaus Wenke.
TA 21 remained in port as a result of fuel quality problems, which also caused the force to leave port at different times: the corvettes at 16.00, R 187 at 16.30 and TA 20 at 19.00, the last with Thorwest on board.
Acting on the information provided by the Yugoslav partisans, the British sortied two 'Hunt Type II' destroyers, Avon Vale and Wheatland, from their base at Ist island at 17.00 on 1 November. Wheatland[/] was commanded by Lieutenant H. A. Corbett and Avon Vale by Lieutenant I. Hall. The destroyers were accompanied by three motor torpedo boats (MTB 295, MTB 287 and MTB 274), three motor gun boats (MGB 642, MGB 638 and MGB 633), and one motor launch (ML 494). The destroyers were tasked with landing a team of South African coastwatchers on the northern tip of Rab island, the motor torpedo boats with patrolling the Kvarner Gulf between Rab and Krk islands, and the rest of the force with loitering to the south-west, near Premuda island. Morgan-Giles was in overall command.
The coastwatchers were landed at 19.50, and at this time the motor torpedo boats reported the sighting of two German 'destroyers' steaming to the south. Using radar, the corvettes detected the British destroyers on their port side at 20.15 and ordered crews to action stations, while UJ 202 fired two star shells. Astern of the two corvettes, the crew of R 187 saw this. The destroyers engaged the German corvettes at 20.20 on a position due west of Lun on Pag island, the British ships each engaging one of the German corvettes. The first British 4-in (102-mm) salvoes hit the corvettes, which were firing rhewir 100-mm (3.94-in) main armament, at a range of 4,000 yards (3660 m). UJ 202 was hit by several shells, and these knocked out her main gun, her bow-mounted 20-mm quadruple cannon mounting, and stern-mounted 37-mm anti-aircraft gun. Her bridge and radio room were also hit, but she continued to return fire while attempting to reach Rab island. UJ 208 was also quickly hit, and her main gun and bow-mounted 20-mm quadruple cannon mounting were knocked out of action. Her crew managed to put out fire on her stern, but another blaze amidships severed all communication between the vessel’s forward and after sections. By 20.30 she had rolled over to port and begun to sink, which she had by 21.00.
The British ships had taken only 10 minutes to disable the corvettes, and then started to pull survivors out of the water, but the rescue effort was suspended at about 22.30, when the approach of TA 20 was spotted on radar. The British ships opened fire on her, the first salvo hitting her bridge and killing all the officer on it and knocking out her fire-control system. TA 20 sank close to Pag island. Neither TA 20 nor either of the corvettes managed to radio news of the attack.
R 187 had maintained radio silence and sailed to the east in order to evade detection, met the convoy sailing from Sibenik at about 23.45, and then escorted it to the north. While 10 of the combat engineer landing craft reached Kraljevica, but two reached Senj as a result of the worsening weather conditions. The rest of the convoy reached Fiume on 2 November as the two British destroyers steamed back to Ist with empty magazines.
As the weather worsened, the British destroyers were able to recover only 90 German survivors before the rescue effort was suspended on the approach of TA 20. Wheatland pulled out of the sea three officers and 68 men. most of them from UJ 202. As it learned of the action, the Germans despatched the corvettes TA 40 and TA 45 as well as the 'E-boats' S 33 and S 154 to search for survivors, finding 17 men of TA 20's crew on the islet of Trstenik on 3 November: the group included seven wounded, who were being tended by the crew of the local lighthouse. Apart from these 17 men, the German vessels rescued one man from UJ 202 and three men of UJ 208. The deteriorating weather also prevented the retrieval of the coastwatchers for four days.
In overall terms, therefore, more than 200 Germans died in this action, this total including the flotilla commander and all three ships' commanding officers.
Yugoslav partisan forces had taken Sibenik and Zadar by 3 November, but the war in the Adriatic theatre continued until April 1945. Allied destroyers engaged no other large German vessels in the Adriatic after November 1944. Dwindling German naval strength in the area resulted in only limited action, while the last recorded loss was TA 45 torpedoed by British motor torpedo boats on 13 April 1945. Only four German vessels survived to be captured or scuttled when the German forces in Italy surrendered at the end of April to the advancing Allied armies.