'JW' was the designation of Allied Arctic convoys (together with a numerical and sometimes a literal suffix) plying from Loch Ewe in north-western Scotland via Iceland to ports of the northern USSR, and inaugurated as successor to the 'PQ' series and as such reciprocals of the 'RA' series (December 1942/May 1945).

There were 22 such convoys. The first was JW.51A of 15/25 December 1942 with 16 merchant vessels and an overall total of 24 escorts, and the last was JW.67 of 12/20 May 1945 with 26 merchant vessels and eight escorts.

Decisive among these convoys was JW.55B, which led to the Battle of the North Cape and the sinking of the battle-cruiser Scharnhorst, effectively ending for some time the period in which German major warships could threaten the Arctic convoys, and JW.58 in which all the Allied vessels arrived safely but the Germans lost three U-boats and six aircraft.

The JW.55B convoy of 20/30 December 1943 was supported by the British 'FV' and attacked by a German surface naval force centred on Scharnhorst in 'Ostfront', but the Germans ships did not make contact with the convoy and Scharnhorst was sunk, in the Battle of the North Cape, by the British battleship Duke of York and a handful of lighter surface vessels.

The convoy comprised 19 laden merchant ships which departed Loch Ewe on 22 December. The close escort was provided by two destroyers and three other escort vessels and the ocean escort by Captain J. A. McCoy’s destroyer Onslow and seven other destroyers of Admiral Sir Bruce Fraser’s Home Fleet. The convoy was also accompanied initially by a local escort group from the UK, and was joined later by the ocean escort of the homebound JW.55A convoy from Murmansk. A covering force comprising Vice Admiral R. Burnett’s light cruiser Belfast with the heavy cruiser Norfolk and light cruiser Sheffield also followed the convoy to provide protection against attack by German surface units. Distant cover was provided by Fraser’s force comprising the battleship Duke of York, light cruiser Jamaica and four destroyers.

The convoy was opposed by the 'Eisenbart' wolfpack of 13 U-boats in the Norwegian Sea. A surface force comprising Scharnhorst and five destroyers was also in readiness in the Altafjord.

The JW.55B convoy departed Loch Ewe in company with its local escort of two corvettes and two minesweepers and two corvettes, and also its close escort. Two days later, on 22 December, it was joined by the ocean escort, while the local escort departed. At the same time the cruiser force from Murmansk and the distant cover force waiting at Akureyri in Iceland, also put to sea, taking station in the Norwegian Sea.

Also on 22 December the convoy was sighted by a patrolling German aeroplane, which then shadowed the convoy and transmitted a sighting report and updates indicating the position, course and speed of the convoy. A succession of aircraft was able to maintain this contact over the next few days. On 25 December the convoy was also sighted by U-601 of the 'Eisenbart' wolfpack, and later in the same day Konteradmiral Erich Bey, in Scharnhorst, received authorisation to sortie with his force. That evening U-716 came close enough to fire on one of the escorts, and U-701 was depth-charged.

On 25 December JW.55B was joined by the ocean escort of JW.55A, which was accompanying the RA.55A returning convoy. Fraser was concerned that a German surface force would reach JW.55B before his force could do so, and ordered the convoy to reverse course. In the event this proved too difficult, but the convoy was slowed to 8 kt in order to assist the meeting.

Scharnhorst was unable to make contact with JW.55B, but on 26 December was intercepted, first by Burnett’s cruisers, then by Fraser’s heavy units, and sunk in the Battle of the North Cape, remaining afloat only long enough to score two minor hits on both Duke of York and the destroyer Saumarez.

Meanwhile the wolfpack had lost contact, and no further contact with JW.55B was achieved by the 'Eisenbart' wolfpack.

On 28 December the convoy was met by the eastern local escort force, three Soviet destroyers and two minesweepers, and arrived at the moth of the Kola inlet leading to Murmansk without further incident on 30 December 1943.

JW.55B’s 19 ships thus reached Murmansk without loss, while the attempt to attack the convoy had led to the loss of the Germans' last operational capital ship in Norway. Thereafter, until the damaged battleship Tirpitz was returned to active service, the Allied Arctic convoys were under no serious threat from the Germans' naval surface forces.

The JW.58 convoy comprised 47 laden merchant ships which departed from Loch Ewe on 27 March 1944. The convoy also included the US light cruiser Milwaukee, which was being transferred to the USSR as part of an agreement over the disposal of the surrendered Italian fleet. The convoy was joined from Iceland by three more ships en route from North America. Close escort was provided by a force led by Lieutenant Commander H. Lambton in the destroyer Westcott, and this close escort force also had another two destroyers and three corvettes. The force was supported in 'FY' by two escort carriers, Activity and Tracker, which travelled with the convoy, and an ocean escort of 17 fleet destroyers under the command of Rear Admiral F. H. G. Dalrymple-Hamilton in the light anti-aircraft cruiser Diadem. In addition, the defence of the JW.58 convoy was supplemented by the 2^nd Support Group, the most British successful anti-submarine warfare group. The 2^nd Support Group comprised five sloops under the command of Captain F. J. Walker in Starling.

The convoy was accompanied initially by local escort groups from the UK and Iceland, and joined later by a local escort group from Murmansk. Distant cover was provide by ships of Admiral Sir Bruce Fraser’s Home Fleet which were engaged in 'Tungsten', an air attack against the German battleship Tirpitz anchored in the Altafjord. Fraser’s ships were the battleships Duke of York and Anson, fleet carrier Victorious, light cruiser Belfast and six destroyers.

Ranged against this force were the U-boats of the German arctic flotilla, 16 U-boats constituting the 'Blitz' (iv), 'Hammer' (iv) and 'Thor' wolfpacks. The German surface naval forces and air forces had been much diminished by this stage of the conflict: Tirpitz was still not operational after damage inflicted by the British X-craft midget submarine attack in 'Source', while the German air force had been reduced by its losses to scouting and shadowing operations.

The JW.58 convoy departed Loch Ewe on 27 March 1944, accompanied by its local escort in the form of two corvettes and three minesweepers. On 29 March the convoy linked with its Iceland contingent and its escort, the frigate Fitzroy and two anti-submarine minesweepers. These were then relieved by the close escort and ocean escort forces, and returned to base.

Later on 29 March Starling encountered U-961 in the Norwegian Sea. This boat was not part of the Arctic flotilla’s wolfpacks, but on passage to North Atlantic: unfortunate enough to encounter the British force, the boat was depth charged and destroyed by Starling and Magpie of the 2^nd Support Group.

On 31 March the JW.58 convoy met the first patrol line, and in the course of the following three days the U-boat force made 18 attacks on the convoy. No ships were hit, but three U-boats were destroyed: on 31 March U-355 was sunk by Beagle and aircraft from Tracker; on 2 April in another encounter Keppel destroyed U-360 in an attack with its 'Hedgehog' bomb projector; and on 3 April a Grumman Avenger aeroplane made a machine gun attack on U-288, after which a Fairey Swordfish aeroplane from Activity attacked the boat and, with help from a Grumman Martlet fighter and Avenger team from Tracker, destroyed it.

On the same day the JW.58 convoy was joined by the eastern local escort of four Soviet destroyers, and on 4 April arrived in the Kola inlet without further incident.

With the safe arrival of so many ships, and the destruction of three U-boats (as well as a fourth incidental kill) and six shadowing aircraft, JW.58 was one of the most successful Arctic convoys. This was also the last Arctic convoy for several months, for the convoy sequence was discontinued during the summer of 1944 as all the British naval forces were required for the 'Neptune' (iii) first stage of 'Overlord'. The Arctic convoys resumed in August 1944 with the JW.59 convoy.