'Eiswolf' was a U-boat wolfpack operation in the Arctic Ocean against the PQ.13 convoy to the northern USSR (28/31 March 1942).

The wolfpack comprised U-209, U-376, U-378, U-435, U-454, U-456, U-585 and U-589, and for the loss of Kapitänleutnant Ernst-Bernward Lohse’s U-585 sank three ships totalling 11,758 tons.

At the same time as PQ.13 was making its outward passage to the USSR, the QP.9 homebound convoy was making for the UK. The 19 ships of the QP.9 convoy departed the Kola Inlet on 21 March, the local escort until 23 March being the Soviet destroyer Gremyashchy and the British minesweepers Gossamer, Harrier, Hussar, Niger and Speedwell. The British ocean escort, present between 21 March and 3 April, comprised the destroyer Offa and minesweepers Britomart and Sharpshooter; the light cruiser Kenya, which should have been with the convoy between 22 and 27 March, did not arrive. The QP.9 convoy passed uneventfully a concentration of U-boats comprising U-209, U-376, U-378 and Korvettenkapitän Adolf Dumrese’s U-655, the last being sunk on 24 March after being rammed by Sharpshooter.

Between 20 and 27 March the PQ.13 convoy of 19 ships passaged from Loch Ewe on the western coast of Scotland to the Hvalfjörður in the south-west of Iceland escorted by the destroyers Sabre, Saladin, Lamerton and Free Polish Błyskawica. On its departure from Iceland the convoy had an ocean escort comprising the British trawlers Blackfly and Paynter and the ex-Norwegian whalers Sulla (sunk in storm on 25 March probably as a result of topside icing leading to a capsize), Silja and Sumba (to be transferred to the USSR), and between 23 and 27 March the destroyers Eclipse and Fury. The light cruiser Trinidad and destroyer Lamerton accompanied the convoy between 23 and 25 March.

Vice Admiral A. T. B. Curteis provided more distant cover, to the north-east of Iceland, with the battleship Duke of York, battle-cruiser Renown, fleet carrier Victorious, light cruiser Nigeria, and a number of destroyers.

Between 24 and 27 March the PQ.13 convoy was widely scattered by a storm, and then in the morning of 27 March a Blohm und Voss Bv 138 flying boat of the 2./Küstenfliegergruppe 406 spotted and reported some of the ships. On the following day U-435, U-436, U-454, U-456, U-585 and U-589 and the destroyers Z 24, Z 25 and Z 26 of Kapitän Gottfried Pönitz’s 8^th Zerstörer-Flottille were ordered to the area for concentrated attacks on the convoy.

Junkers Ju 88 twin-engined medium bombers of Hauptmann Hajo Hermann’s III/Kampfgeschwader 30 sank two scattered freighters, the 4,815-ton Panamanian Raceland and 7,007-ton British Empire Ranger.

On 29 March the British destroyer Oribi and Soviet destroyers Gremyashchy and Sokrushitelny arrived from the Kola inlet to bolster the convoy’s escort strength. Z-26 sank the straggling 4,687-ton Panamanian Bateau, and the three German destroyers then encountered Trinidad running ahead of the convoy with Fury. In confused engagements impeded by a heavy snowstorm, Trinidad hit Z-26 and rendered her unmanoeuvrable, but was then hit by one of her own torpedoes despatched to finish off the destroyer: the cruiser was later bombed and sunk of her way back to the UK. In the mêlée Z-24 and Z-25 managed to rescue 88 men from the sinking Z-26, hit Eclipse heavily and escape after a short exchange with Oribi and Sokrushitelny; eight more of Z-26's survivors were rescued by U-378. Kapitänleutnant Ernst-Bernward Lohse’s U-585 was attacked by Fury as it closed on the disabled Trinidad, but was lost later, probably on 30 March, in the Germans' own 'Bantos A' minefield.

On 30 March the 6^th Minesweeping Flotilla (Harrier, Gossamer, Speedwell and Hussar), which had departed Murmansk two days earlier, reached the convoy. U-209 and U-456 sighted and fired on several ships but their torpedoes missed. Kapitänleutnant Friedrich-Karl Marks’s U-376 and Kapitänleutnant Siegfried Strelow’s U-435 sank two stragglers, the 5,086-ton British Induna and 6,421-ton US Effingham, the latter having already been damaged by U-456. On 1 April U-589 fired on but missed a destroyer.

The Soviet submarines K-21, K-22, Shch-404 and Shch-421, which had been established as a flank guard of the convoy against against surface vessel attacks, left for the Arctic coast on 1 April, where Shch-404 sank the 2,318-ton German freighter Michael off the Tanafjord. On 3 April, in Svaerholthavet, K-22 attacked but missed a minesweeping force comprising M-1505, M-1506 and M-1508. Other attacks by K-21, Shch-404, Shch-421, M-176 (three times), M-171, M-173 and M-174 in the Varangerfjord between 28 March and 3 April achieved no success.