Convoy PQ 13 (20 March – 2 April 1942) was a British Arctic convoy that delivered war supplies from the Western Allies to the USSR during the Second World War. The first days of the voyage were quiet but on 25 March a storm blew up and lasted for three days. On 28 April, when the storm had abated, the convoy had been scattered for westwards from the North Cape (). The convoy escorts, led by the cruiser , manged to concentrate the merchant ships into two groups apart, with several stragglers unaccounted for.

The clear weather revealed the ships to reconnaissance aircraft and the ships were attacked during the day, two ships being sunk and others damaged. Using Ultra decrypts the Admiralty warned the convoy commander about some of the air attacks and U-boat search zones. Three German destroyers sailed from Kirkenes to intercept the ships and combed the track of the convoy, sinking one ship and taking the crew prisoner. Ultra decrypts gave much detail on the destroyer sortie and during the night of 28/29 March, Trinidad and the destroyer Fury lay in wait.

At on 29 March Trinidad detected the German destroyers on radar and hit with its second salvo. Skirmishing between blizzards of snow, Trinidad was hit by one of its torpedoes and severely damaged. Z 26 was sunk by the destroyer Eclipse and Trinidad managed to reach Murmansk. As the merchant ships came close to Murmansk, two were torpedoed and sunk by U-boats. Ships arrived at Murmansk in groups or individually until 2 April.

Five ships were sunk of the 19 starters and this alarmed Admiral John Tovey, the commander of the Home Fleet and the First Sea Lord, Admiral Dudley Pound, that the German operation against the convoy foreshadowed more combined-arms attacks against Arctic convoys. As the hours of daylight increased, the weather improved and the number of German U-boats and aircraft increased, they predicted that convoy losses could only increase. The Germans thought that five ships was a poor exchange for the loss of a destroyer, a U-boat and several aircraft.

Background

Arctic Ocean

Between Greenland and Norway are some of the most stormy waters of the world's oceans, of water under gales full of snow, sleet and hail. Around the North Cape and the Barents Sea the sea temperature rarely rises about and a man in the water would probably die of exposure unless rescued immediately. The cold water and air made spray freeze on the superstructure of ships, which had to be removed quickly to avoid the ship becoming top-heavy. The cold Arctic water is met by the Gulf Stream, warm water from the Gulf of Mexico, which becomes the North Atlantic Drift. Arriving at the south-west of England, the drift moves between Scotland and Iceland.

North of Norway the drift splits, one stream goes north of Bear Island to Svalbard and the southern stream follows the coast of Murmansk into the Barents Sea. The mingling of cold Arctic water and warmer water of higher salinity generates thick banks of fog for convoys to hide in but the waters drastically reduce the effectiveness of Asdic as U-boats moved in waters of differing temperatures and density. In winter, polar ice could form as far south as off the North Cape, forcing ships closer to Luftwaffe air bases or being able to sail further out to sea in summer, when the ice can recede northwards as far as Svalbard. The region is in perpetual darkness in winter and permanent daylight in the summer which made air reconnaissance almost impossible or easy.

Arctic convoys

In October 1941, after Operation Barbarossa, the German invasion of the USSR, which had begun on 22 June, the Prime Minister, Winston Churchill, made a commitment to send a convoy to the Arctic ports of the USSR every ten days and to deliver a month from July 1942 to January 1943, followed by and another more than already promised. The first convoy was due at Murmansk around 12 October and the next convoy was to depart Iceland on 22 October. A motley of British, Allied and neutral shipping loaded with military stores and raw materials for the Soviet war effort would be assembled at Hvalfjörður in Iceland, convenient for ships from both sides of the Atlantic.

By late 1941, the convoy system used in the Atlantic had been established on the Arctic run; a convoy commodore ensured that the ships' masters and signals officers attended a briefing before sailing to make arrangements for the management of the convoy, which sailed in a formation of long rows of short columns. The commodore was usually a retired naval officer, aboard a ship identified by a white pendant with a blue cross. The commodore was assisted by a Naval signals party of four men, who used lamps, semaphore flags and telescopes to pass signals, coded from books carried in a bag, weighted to be dumped overboard. In large convoys, the commodore was assisted by vice- and rear-commodores who liaised with the escort commander and directed the speed, course and zig-zagging of the merchant ships.

Signals intelligence

Bletchley Park

The British Government Code and Cypher School (GC&CS) based at Bletchley Park housed a small industry of code-breakers and traffic analysts. By June 1941, the German Enigma machine Home Waters () settings used by surface ships and U-boats could quickly be read. On 1 February 1942, the Enigma machines used in U-boats in the Atlantic and Mediterranean were changed but German ships and the U-boats in Arctic waters continued with the older (Hydra from 1942, Dolphin to the British). By mid-1941, British Y-stations were able to receive and read Luftwaffe W/T transmissions and give advance warning of Luftwaffe operations. In 1941, naval Headache personnel, with receivers to eavesdrop on Luftwaffe wireless transmissions, had been embarked on warships.

B-Dienst

The rival German (, Observation Service) of the (MND, Naval Intelligence Service) had broken several Admiralty codes and cyphers by 1939, which were used to help Kriegsmarine ships elude British forces and provide opportunities for surprise attacks. From June to August 1940, six British submarines were sunk in the Skaggerak using information gleaned from British wireless signals. In 1941, read signals from the Commander in Chief Western Approaches informing convoys of areas patrolled by U-boats, enabling the submarines to move into "safe" zones. broke Naval Cypher No 3 in February 1942 and by March was reading up to 80 per cent of the traffic but not fast enough for the results to have tactical effect and relied on traffic analysis.

Prelude

tactics

As soon as information was received about the assembly of a convoy, would send long-range reconnaissance aircraft to search Iceland and northern Scotland. Once a convoy was spotted, aircraft were to keep contact as far as possible in the extreme weather of the area. If contact was lost its course at the last sighting would be extrapolated and overlapping sorties would be flown to regain contact. All three were to co-operate as the convoy moved through their operational areas. would begin the anti-convoy operation east to a line from the North Cape to Spitzbergen Island, whence would take over using his and the aircraft of , that would fly to Kirkenes or Petsamo to stay in range. was not allowed to divert aircraft to ground support during the operation. As soon as the convoy came into range, the aircraft were to keep up a continuous attack until the convoy docked at Murmansk or Arkhangelsk.

German air-sea rescue

The Luftwaffe Sea Rescue Service () along with the , the Norwegian Society for Sea Rescue (RS) and ships on passage, recovered aircrew and shipwrecked sailors. The service comprised at Stavanger covering Stavanger, Bergen and Trondheim and at Kirkenes for Tromsø, Billefjord and Kirkenes. Co-operation was as important in rescues as it was in anti-shipping operations if people were to be saved before they succumbed to the climate and severe weather. The sea rescue aircraft comprised Heinkel He 59 floatplanes, Dornier Do 18 and Dornier Do 24 seaplanes. (OKL, high command of the ) was not able to increase the number of search and rescue aircraft in Norway, due to a general shortage of aircraft and crews, despite Stumpff pointing out that coming down in such cold waters required extremely swift recovery and that his crews "must be given a chance of rescue" or morale could not be maintained.

U-boats From January to the end of March 1942, 18 new Type VII U-boats were sent to Norway from Germany, increasing the number to 25. The boats were under the command of Admiral Hubert Schmundt, the . The U-boats at Kirkenes and Narvik had to sail south to Trondheim for serious repairs. During the perpetual darkness of the winter of 1941 to 1942 the U-boats found nothing in February, three PQ convoys of fifty ships reached Murmansk and the reciprocal QP convoys evaded attack. On 6 March, the sailed against Convoy PQ 12 and the return Convoy QP 8. Four of the Kirkenes U-boats took up ambush positions off the Kola Inlet and two boats from Narvik sailed with Tirpitz. The new U-boat was attacked by aircraft but escaped damage. Convoy PQ 12 was spotted by that homed into the area but the convoy arrived intact. Admiral Karl Dönitz the Befehlshaber der U-Boote (BdU, Commander, U-boats) berated the (SKL) for sending the boats too close to Murmansk, denying them room to manoeuvre.

Convoy

Convoy PQ 13 comprised seven British ships, including the tanker , four US freighters, one Polish, four of Panamanian and one ship of Honduran registry. The Convoy Commodore was Dennis Casey in River Afton. On 10 March, the convoy was escorted for the first stage of its voyage, Loch Ewe in Scotland to Iceland, by the Western Local Escort, comprising two destroyers and an anti-submarine warfare (ASW) trawler. From Iceland to the Soviet Union, departing on 20 March, the convoy had an ocean escort of a Crown Colony-class cruiser, two destroyers and two trawlers, augmented by three whalers being transferred to the Soviet Navy. The Ocean Escort was commanded by Captain Leslie Saunders in the cruiser .

Home Fleet

In support of the convoy escort, guarding against a sortie by Tirpitz and the other big ships based in Norway, was a Heavy Cover Force from the Home Fleet, comprising the battleships (Vice Admiral Alban Curteis commanding) , battlecruiser , aircraft carrier , the cruisers and and sixteen destroyers, , , , , , , , , , , , , , , and . The Heavy Cover Force was to follow the track of the convoy at long distance, until the convoy was past Bear Island and then cover Convoy QP 9 the reciprocal convoy. The Home Fleet had a unique Special W/T procedure SWT) that used unusual wireless frequencies, used no call-signs and transmitted messages in a way that made it difficult to know that they were naval transmissions. During the convoy, attempts to use the SWT failed.

Voyage

20−23 March

The first stage escort, three ships bound from Reykjavík to Murmansk and the close escort for the voyage joined Convoy PQ 13 and sailed from Reykjavík on 20 March. The convoy was helped by a powerful south-westerly wind and soon after noon on 23 March, when around to the south-east of Jan Mayen the convoy turned to the east after the Admiralty had received a decrypted Enigma signal giving the position of U-boat search line and during the unscheduled turn, the fleet oiler Oligarch and its escort, Lamerton made rendezvous with the Home Fleet to fuel its destroyer escorts.

24 March