CAMPAIGN SUMMARIES OF WORLD WAR 2

GERMAN U-BOATS AT WAR, Part 4 of 6

 1943

1943

JANUARY 1943

Atlantic

Russian Convoys - Russian convoy JW52 and return RA52 both set out in January. Of the 25 ships in the two convoys, one left JW52 to return to port, and one merchantmen with RA52 was lost to U-boat attacks.

Battle of the Atlantic - Severe weather and evasive convoy routing kept losses down in January 1943. However, south of the Azores, out of range of air cover, Trinidad/Gibraltar tanker convoy TM1 lost seven out of nine ships to U-boats.

Monthly Loss Summary, including Russian Convoys
- 30 British, Allied and neutral ships of 189,000 tons in the Atlantic from all causes
- 4 U-boats including 1 by RAF in North Atlantic; 2 by US aircraft off Brazil; 1 by unknown causes

Europe

Air War - RAF Bomber Command by night and increasingly the USAAF by day mounted a growing attack on Germany and occupied Europe. U-boat bases and their production centres were major targets in 1943, yet in the first six months, not one U-boat was destroyed in air-raids and the construction programmes were hardly affected. Throughout the war not one U-boat was lost in the incredibly strong, reinforced concrete shelters built by the Germans at their main bases including on the French west coast.

Mediterranean

Casablanca Conference - Prime Minister Churchill and President Roosevelt with their Chiefs of Staff meet for this important conference. Major areas for discussion included the European invasion in 1944, landings in Sicily and Italy after the Tunisian campaign, the bombing of Germany and the continuation of the war in Burma and the Pacific. Losses due to U-boats and the shortage of shipping proved to be significant constraints on Allied plans.

13th - Axis attacks continue against Allied ships in Algerian ports and convoys off the coast. Canadian corvette "Ville de Quebec" sank "U-224" west of Algiers.

 21st - Submarine "Sahib" on patrol off western Corsica sank "U-301".

PROSPECTS FOR ALLIED VICTORY   - The Russians gained a famous victory with the German surrender at Stalingrad in January 1943. Taken with the October 1942 British Battle of El Alamein and June 1942 American Battle of Midway, the three Allied successes are usually considered as marking the turning point in the 40 month old war against the Axis powers. The Battle for Guadalcanal, ending as it did Japanese hopes of controlling the South West Pacific should also be added to this roll-call of victory. However, more than 30 months of struggle and bloodshed had to be endured before victory was certain. Even then, one battle was not over until the very end - the Battle of the Atlantic against the U-boat, although it did peak over the next four months.

FEBRUARY 1943

Atlantic

Attack on Slow Halifax/UK Convoy SC118 - SC118, escorted by the British B2 group was heavily attacked in mid-Atlantic. A total of 20 U-boats sank 13 of the 63 merchantmen. However, on the 4th "U-187" was detected by HF/DF, hunted down and sunk by destroyers "Beverley" and "Vimy". Three days later, Free French corvette "Lobelia" sank "U-609" and a RAF B-17 Flying Fortress accounted for "U-624".

17th - Slow UK/North America convoy ONS165 and the escorting British B6 group were attacked east of Newfoundland. "U-201" was sunk by destroyer "Fame" and "U-69" by "Viscount". Only two merchantmen were lost.

22nd - U-boats attacked ON166 and its American A3 group in mid-Atlantic and sank 14 ships in the course of four days. In exchange "U-606" was depth-charged to the surface by Polish destroyer "Burza" and Canadian corvette "Chilliwack", and finished off by ramming by US Coast Guard cutter "Campbell".

22nd - Mines laid by "U-118" in the Strait of Gibraltar sank three merchantmen and on the 22nd Canadian corvette "WEYBURN" as she escorted North Africa/UK convoy MKS8.

23rd - UK/Caribbean tanker convoy UC1 lost badly to U-boats, but southwest of Madeira, "U-522" was sent to the bottom by cutter "Totland".

Russian Convoys - Russia-bound convoy JW53 sailed with 28 merchantmen. Six turned back because of the weather, but the rest reached Kola Inlet on the 27th. Return convoy RA53 with 30 ships lost three to U-boats in March. These were the last convoys to or from Russia until November 1943 - a gap of nine months, because of the pressure of events in the North Atlantic

Monthly Loss Summary
- 50 British, Allied and neutral ships of 310,000 tons in the Atlantic from all causes, 1 corvette
- 15 U-boats including 5 by RAF in North Atlantic and off Portugal and Gibraltar; 2 by RAF and US aircraft on Bay of Biscay patrols; 1 by US Navy in North Atlantic.

Mediterranean

1st - As cruiser-minelayer "WELSHMAN" sailed from Malta to Alexandria after minelaying operations in the Strait of Sicily, she was sunk by "U-617" north of Bardia.

North Africa - As Rommel prepared his Mareth line defences in southern Tunisia, Eighth Army units crossed the border from Libya on the 4th. All Libya was now in Allied hands and the Italian North African Empire ceased to exist.

17th - "U-205" attacked Tripoli/Alexandria convoy TX1 northwest of Derna, and was then sunk by South African aircraft of No 15 Squadron and destroyer "Paladin".

19th - Combined air and sea attacks also accounted for "U-562" northeast of Benghazi. This time the convoy was Alexandria/Tripoli XT3, the warships destroyers "lsis" and "Hursley" with aircraft from No 38 Squadron RAF.

23rd - German and Italian operations against Allied shipping off Algeria led to further losses on both sides. A patrol of escort destroyers "Bicester", Easton", Lamerton" and Wheatland" shared in the sinking of "U-443" to the northwest of Algiers.

MARCH 1943

Atlantic

4th - In operations against the US/Gibraltar routes, "U-87" was sunk off Portugal by Canadian destroyer "St Croix" and corvette "Shediac".

11th - North American/UK convoy HX228 (60 ships), escorted by the British B3 group, lost a total of four ships. Destroyer "Harvester" rammed "U-444" but was disabled and the U-boat had to be finished off by French corvette "Aconit". "HARVESTER", now stationary, was sunk by "U-432" which in turn was brought to the surface in mid-Atlantic by "Aconit's" depth charges and finally destroyed by gunfire and ramming.

Battle of the Atlantic - Throughout the war a large proportion of the losses due to U-boats were among independently routed merchantmen and stragglers from convoys, but in March 1943 the Germans came close to overwhelming well escorted convoys. Between the 7th and 11th, slow convoy SC121 lost 13 ships. Worse was to come between the 16th and 20th in the largest convoy battle of the war - around HX229 and SC122. Over 40 U-boats were deployed against the two as they slowly coalesced in the mid-Atlantic air gap until there were 100 ships plus escorts. Twenty U-boats took part in the attack and sank 21 merchantmen before additional air and surface escorts finally drove them off. A RAF Sunderland accounted for the one U-boat destroyed. Again the German B-Service was responsible for providing Doenitz' packs with accurate convoy details and routeing. These losses took place at another turning point in the secret war around the Enigma codes. Early in the month the U-boats changed from three-rotor to the far more complex four-rotor 'Triton' code. Yet by month's end this had been broken by the men and women of Bletchley Park and their electromechanical computers. The Allies' tremendous advantage was restored. This came at the same time as a number of other developments, which together brought about a complete reversal in the war against the U-boats. The first five Royal Navy support groups with modern radars, anti-submarine weapons and HF/DF were released for operation in the North Atlantic. Two were built around Home Fleet destroyers, two around Western Approaches escorts, including Capt Walker's 2nd Escort Group, and one with escort carrier "Biter". Escort carriers "Archer" and the American "Bogue" were also ready for action, but "Dasher" was unfortunately lost in UK waters. Nevertheless, the mid-Atlantic air gap was about to be finally closed. Another major breakthrough was again in the air war. Aircraft were being fitted with the 10cm wavelength radar which was undetectable by U-boat Metox receivers. The new radar and the Leigh light made a powerful weapon against surfaced submarines, especially as they tried to break out through the Bay of Biscay air patrols. More VLR aircraft were also joining Coastal Command to extend further the Allies grip on the convoy routes throughout their length.  

Monthly Loss Summary
- 90 British, Allied and neutral ships of 538,000 tons in the Atlantic from all causes, 1 destroyer
- 12 U-boats including 4 by the RAF in North Atlantic; 1 by RAF Bay of Biscay patrols; 1 by US aircraft off Barbados; 2 by US forces off the Azores and Canary Islands; 1 by unknown causes

APRIL 1943

Atlantic

2nd - "U-124" on passage to the Freetown area encountered UK/West Africa convoy OS45 to the west of Portugal. Two merchant ships were sunk, but she was attacked by sloop "Black Swan" and corvette "Stonecrop" of the 37th EG and sunk in turn.

6th - In attacks on Halifax/UK convoy HX231 southwest of Iceland, two U-boats were lost - "U-635" to frigate "Tay" of the British B7 group and "U-632" to a RAF Liberator. Six of the convoy's merchantmen were lost to the 15-boat pack. (Note: the identity of these two U-boats is sometimes reversed.)

7th - Submarine "Tuna" on Norwegian Arctic patrol sank "U-644" northwest of Narvik.

11th - Destroyer "BEVERLEY" of the British B6 group escorting convoy ON176 was sunk south of Greenland by "U-188".

18th - "U-123" on patrol south of Freetown torpedoed and sank "P-615" (ex-Turkish) on passage to the South Atlantic Command to provide anti-submarine training.

Battle of Slow UK/North America Convoy ONS4 - ONS4 (these convoys were renumbered starting in March) was escorted by the British B2 group (Cdr Macintyre) and reinforced by the 5th Escort Group with escort carrier "Biter". On the 23rd "U-191" was detected to the south of Greenland by HF/DF and sunk by destroyer "Hesperus" using the Hedgehog forward-throwing A/S mortar (pictured below). Two days later on the 25th a Swordfish of 811 Squadron from "Biter" found "U-203" and destroyer "Pathfinder" finished her off.

Battle of the Atlantic - U-boat strength was up to 425 with 240 boats operational, and over half of them on passage through or on patrol throughout the North Atlantic. However, there was somewhat of a lull until the end of the month with the start of the ONS5 battle. A group also operated once again in the weakly defended Sierra Leone area. In just one night "U-515" sank seven of the 18 ships in Takoradi/Sierra Leone convoy TS37. Changes were again made in the Allies' responsibility for the North Atlantic routes. As agreed at the March 1943 Atlantic Convoy Conference in Washington: (1) Royal Canadian Navy was to exercise full control of the northerly routes west of the 47-00'W CHOP line - approximately south of Greenland; (2) Royal Navy took over to the east of 47-00'W; (3) US Navy was to look after the southerly convoys,and also the CU/UC tanker routes between the West lndies and UK. With these organisational changes, the far more effective convoy Escort Groups, and the developments described in March, the scene was set for the decisive convoy battles of May 1943.

Monthly Loss Summary
- 40 British, Allied and neutral ships of 242,000 tons in the Atlantic from all causes, 1 destroyer and 1 submarine
- 14 German and 1 Italian U-boats including 3 by the RAF in the North Atlantic and off the Canaries; 1 by RAF Bay of Biscay patrol; 1 by RAF-laid mine in the Bay of Biscay; 1 by RAAF north of the Faeroes; 3 to US forces in the North and South Atlantic, including the one Italian

MAY 1943

Atlantic

United States - Winston Churchill travelled across the Atlantic in the troopship "Queen Mary together with 5,000 German POWs for the Trident Conference, the third major meeting in Washington DC.

The May 1943 Convoy Battles - Victory of the Escorts At the beginning of the month over 40 U-boats were deployed in three patrol lines off Greenland and Newfoundland. Another group operated to the far west of the Bay of Biscay. A number were passing through the northern transit area and over 30 on passage between their Biscay bases and the North Atlantic. More still were on patrol in the South Atlantic or passing through. There were numerous Allied convoys crossing the North Atlantic as suitable targets, starting with ONS5: (1) Slow UK/North America ONS5 - On the 21st April, ONS5 sailed with 42 ships from Liverpool outward bound for North America. Escort was provided by the British B7 group (Cdr P. W. Gretton) with two destroyers, a frigate, four corvettes and two trawlers. The first threat was dealt with before the end of April when "U-710" was sunk by an escorting RAF B-17 Flying Fortress south of Iceland. The real battle started in early May, south of Greenland as all three U-boat patrol lines closed in. Before they arrived the escort was reinforced by the 3rd Escort Group (EG) from St John's, Newfoundland. Rough seas made refuelling difficult and some of the escorts had to leave. The 1st EG, also from St John's sailed to replace them. Over the next few days 13 merchantmen were lost, but at a cost of a further six U-boats. All went down in often confused fighting to the south of Greenland or northeast of Newfoundland. More still were damaged. Type 271 radar played a large part in the escort's successes: 4th - "U-630" to a RCAF Canso (Catalina). 5th - B7 group corvette "Pink" sank "U-192", sister ship "Loosestrife", also from B7 sank "U-638". 6th - B7 group destroyer "Vidette" sank "U-125". Destroyer "Oribi" detached from convoy SC127 to join B7 together with corvette "Snowflake" accounted for "U-531". (The identity of "U-125" and "U-531" is reversed in some sources.) Finally, "U-433" was sunk by sloop "Pelican" of the 1st EG. The surviving U-boats were regrouped for attacks on other convoys, but in the area south of Greenland/northeast of Newfoundland as well as throughout the North Atlantic, merchantmen sinkings went down as U-boat losses mounted alarmingly. Much of this was due to the way escort groups (EG) moved from one convoy to another to support the existing escorts. The number of convoys crossing the North Atlantic in both directions was truly impressive and the main movements in May, together with the U-boats sunk is listed here: (2) North America/UK HX236 - 46 ships escorted by British B1 group and 2nd EG (Capt Walker); no merchant ship losses 11th - "U-528" was damaged by US aircraft in an earlier attack on ONS5. Now southwest of Ireland, she was sunk by sloop "Fleetwood" and RAF aircraft of No 58 Squadron. (3) Slow UK/North America ONS6 - 31 ships escorted by British B6 group and 4th EG with escort carrier "Archer"; no merchant ship losses. (4) North America/UK HX237 - 46 ships escorted by Canadian C2 group and 5th EG with escort carrier "Biter". Three stragglers sunk in exchange for possibly three U-boats in mid-Atlantic: 12th - "U-89" to destroyer "Broadway" and frigate "Lagan", both of C2 group, assisted by Swordfish of 811 Squadron from "Biter". 12th - RAF B-24 Liberator of No 120 Squadron damaged either "U-456" or "U-753", which may had been finished off by destroyer "Pathfinder" of the 5th EG. Alternatively one of these U-boat may have gone missing on the 15th. (Sources vary.) 13th - Either "U-456" or "U-753" was then detected by RCAF Sunderlands of No 423 Squadron which brought up frigate "Lagan" and Canadian corvette "Drumheller" to sink the U-boat. (5) North America/UK SC129 - 26 ships escorted by British B2 group, with 5th EG transferred from HX237 on the 14th. Two merchant ships lost in mid-Atlantic for two U-boats: 12th - "U-136" to destroyer "Hesperus" of B2 (Cdr Macintyre). 14th - "U-266" to a RAF B-24 Liberator of No 86 Squadron. (6) UK/North America ON182 - 56 ships escorted by Canadian C5 group, with 4th EG and carrier "Archer" transferred from ONS6; no merchant ship losses. (7) North America/UK HX238 - 45 ships escorted by Canadian C3 group; no merchant ship losses. (8) Slow UK/North America ONS7 - 40 ships escorted by British B5 group, with 3rd EG transferred from ONS5. One ship lost for two U-boats destroyed in the vicinity of the convoy to the southeast of Greenland and south of Iceland: 14th - "U-657" to a US Navy Catalina. 17th - "U-640" to frigate "Swale" of B5. (The identity of "U-657" and "U-640" was reversed in some sources.) (9) UK/NorthAmerica ON183 - 32 ships escorted by British B4 group, no merchant ship losses. (10) North America/UK SC130 - 38 ships escorted by British B7 group, with 1st EG transferred from ONS5. No merchant ship losses in exchange for four U-boats south of Greenland: 19th - "U-954" to a RAF Liberator; "U-209" to frigates "Jed" and "Sennen" of 1st EG; and "U-381" to destroyer "Duncan and corvette Snowflake of B7. 20th - "U-258" to another RAF Liberator - both VLR aircraft from the very successful No 120 Squadron. (11) UK/NorthAmerica ON184 - 39 ships escorted by Canadian C1 group and US 6th EG with escort carrier "Bogue". No merchant ship losses in exchange for one U-boat: 22nd - "U-569" in mid-Atlantic to Avengers flying from "Bogue". (12) North America/UK HX239 - 42 ships escorted by British B3 group and 4th EG and carrier "Archer" transferred from ON182 (and before that ONS6). No merchant ship losses in exchange for one more U-boat: 23rd - In the first success with aircraft rockets, "U-752" in mid-Atlantic was badly damaged by "Archer's" Swordfish of 819 Squadron, and scuttled as surface escorts approach. By the 24th, U-boat losses were so heavy and the attacks so fruitless, Adm Doenitz ordered his captains to leave the North Atlantic battlefield. They either returned home or concentrated on the US/Gibraltar routes. It was some time before the Allies realised the North Atlantic was almost free of U-boats. The British and Allied air and sea escorts were winning. 26th - "U-436" was sunk west of Cape Ortegal, Spain by frigate "Test" and Indian corvette "Hyderabad". (13) North America/UK SC131 - 31 ships escorted by British B6 group, 3rd and 40th EGs ; no merchant ship losses. (14) Slow UK/North America ONS8 - 52 ships escorted by Canadian C4 group and 2nd EG (Capt Walker) transferred from HX236 ; no merchant ship losses. (15) North America/UK HX240 - 56 ships escorted by Canadian C5 group and 2nd EG from ONS8. No merchant ship losses in exchange for one U-boat: 28th - "U-304" to a RAF Liberator of No 120 Squadron south of Greenland. Summary statistics for these North Atlantic convoy actions 15 convoys totalling 622 merchantmen seven British B and five Canadian C convoy groups six British and one US supporting Escort Groups three escort carriers Well over 70 U-boats at sea 23 German U-boats sunk 11 convoys were unscathed, four convoys lost 19 ships - a loss rate of 3 percent Without the heavy losses of ONS5, loss rate was 1 percent Without the U-boats sunk in attacks on OSN5, 16 U-boats were lost in exchange for 6 merchantmen

Monthly Loss Summary
- 40 British, Allied and neutral ships of 204,000 tons in the Atlantic from all causes
- 37 German and 1 Italian U-boats. In addition to those lost in or around the convoy battles: 3 by RAF in North Atlantic; 6 by RAF and RAAF Bay of Biscay patrols; 4 by US forces in the North Atlantic, off Florida and Brazil; 2 by collision in the North Atlantic

Mediterranean

21st - Submarine "Sickle" on patrol south of Toulon, France torpedoed and sank "U-303".  

25th - Four days later escorting corvette "Vetch" sank "U-414" northeast of Oran.

Merchant Shipping War - The end of the Tunisian campaign marked a major upturn in the fortunes of Allied shipping. By mid-month minesweepers had cleared a channel through the Strait of Sicily, and the first regular Mediterranean convoys since 1940 were able to sail between Gibraltar and Alexandria. The long haul around the Cape of Good Hope to the Middle East was no longer necessary. The opening of the Mediterranean was equivalent to commissioning a large amount of new Allied merchant ship tonnage.

Indian & Pacific Oceans

Merchant Shipping War - Adm Somerville's Eastern Fleet had lost its remaining big ships to other theatres. An inadequate anti-submarine and escort force was left to deal with the submarines active in the Indian Ocean. Japanese boats were again being joined by German U-boats, and right through until December 1943 not many more than a dozen German and Japanese boats inflicted quite heavy losses throughout the length and breadth of the Indian Ocean. Between June and year's end they sank over 50 merchantmen.

DEFENCE OF TRADE - January 1942 to May 1943

Total Losses = 2,029 British, Allied and neutral ships of 9,792,000 tons ( 576,000 tons per month)

By Location

Location	Number of British, Allied, neutral ships	Total Gross Registered Tonnage
North Atlantic	1,234	6,808,000 tons
South Atlantic	97	611,000 tons
UK waters	105	248,000 tons
Mediterranean	129	598,000 tons
Indian Ocean	230	873,000 tons
Pacific Ocean	234	654,000 tons

By Cause

Causes * in order of tonnage sunk (1., 4. ... - Order when weapon first introduced)	Number of British, Allied, neutral ships	Total Gross Registered Tonnage
1. Submarines	1,474	8,048,000 tons
4. Aircraft 5. Other causes 6. Raiders 2. Mines 3. Warships 7. Coastal forces	169 228 31 71 31 25	814,000 tons 348,000 tons 202,000 tons 172,000 tons 130,000 tons 78,000 tons

JUNE 1943

Atlantic

1st - After supporting convoys ONS8 and HX240, Capt Walker's 2nd EG located "U-202" south of Greenland. She was sunk by sloop "Starling".

Bay of Biscay Patrols - Aircraft of Coastal Command continued covering U-boat exit routes from western France and were joined by surface escort groups covered by cruisers. At the same time U-boats were fitted with heavy AA armament to enable them to fought their way out on the surface in groups. U-boat sinkings went down as Allied aircraft losses mounted, but four U-boats were destroyed: 1st - "U-418" to a rocket-firing RAF Beaufighter. 14th - "U-564" to a RAF Whitley. 24th - The 2nd EG (Capt Walker) accompanied by cruiser "Scylla" accounted for two submarines northwest of Cape Ortegal, NW Spain. Tanker "U-119" was brought to the surface and rammed by "Starling". With her Asdic out of action from the ramming, "Starling" left the sinking of "U-449" to "Wren", "Woodpecker", "Kite" and "Wild Goose".

Northern Transit Area - In the waters through which Norwegian-based U-boats had to sail for their patrol areas, two submarines were sunk: 4th - Submarine "Truculent" on anti-U-boat patrol between Norway and Iceland sank "U-308" north of the Faeroe Islands. 11th - A RAF Fortress accounted for "U-417" in the same northern transit area.

14th - In the North Atlantic "U-334" and other U-boats simulated the radio transmissions of large wolf packs. She was located and sunk by frigate "Jed" and sloop "Pelican" of the 1st EG.

Battle of the Atlantic - The Royal Navy had finally changed the convoy codes and made them secure against the work of the German B-Service. In contrast, the British 'Ultra' work was fully integrated into the Admiralty U-boat Tracking Room, and an almost complete picture of German Navy and U-boat operations was available. Not one North Atlantic convoy was attacked during the month although U-boats were operating around the Azores. As Allied air and sea forces grew in strength and effectiveness, especially through the use of 10cm radar and 'Ultra', Adm Doenitz sought other ways to regain the initiative. This he was never able to do, although right through until the last day of the war, the Allies could not relax their efforts, and continually introduced new detection systems, weapons and tactics. Against numerous, well-trained and effectively used escorts, the day of the conventional submarine was drawing to a close. The Germans placed much faith in the Walther hydrogen peroxide boat now under development, which with its long underwater endurance and high speed, would have proved a formidable foe, but it did not get beyond the experimental stage by war's end. An interim step on the road towards the 'true' submarine started at the end of 1943 with the design and building of Type XXI ocean and XXIII coastal boats. Using the streamlined hull of the Walther and high capacity batteries, their underwater speed made them faster than most escorts. Fortunately for the Allies they did not enter service in numbers until too late in 1945. For now the Germans had to rely on the U-boats currently in service and building. Total numbers stayed at around the 400 mark for the remainder of the war, in spite of a 40 boat per month construction programme, and various steps were taken to improve their offensive and defensive capability. Apart from extra AA armament, the Gnat acoustic torpedo was introduced specifically to combat the convoy escorts. Its first test came in September 1943. Before then in July, the schnorkel, a Dutch development that allowed batteries to be recharged at periscope depth, started trials. It did not enter general service until mid-1944, but then went quite some way to nullifying the radar of the air escorts and patrols. Even now the German Navy was unaware the Allies were using short wavelength radar, but when they did, early in 1944, an effective detector was shortly introduced.

Monthly Loss Summary
- 7 British, Allied and neutral ships of 30,000 tons in the Atlantic from all causes,
- 16 German and 1 Italian U-boats including 4 by US and RAF aircraft off Iceland and the Strait of Gibraltar, and the Italian boat in the North Atlantic; 3 by the US Navy, one off the east coast of America and two to escort carrier "Bogue" off the Azores; 1 by French aircraft off Dakar.

JULY 1943

Atlantic

15th - "U-135" attacked UK/West Africa convoy OS51 off the Canary Islands, and was depth-charged by the escort including sloop "Rochester" and corvette "Balsam". She was sunk when corvette "Mignonette" rammed.

24th - After six months effort the bombing campaign against U-boat bases claimed its first success on the 24th when "U-622" was badly damaged in a USAAF raid on Trondheim, Norway and paid off.

30th - The Bay of Biscay offensive by the RAF and Australian, Canadian and American aircraft reached a peak and since March 1943, 10 U-boats had been sunk and many others damaged. On the 30th, two 'milchcows', "U-461" and "U-462" escorted by "U-504", were located to the northwest of Cape Ortegal, Spain. In a running battle "U-461" was finally sunk by Sunderland U/461 of RAF No 461 Squadron. "U-462" also went down in the fighting. Capt Walker's 2nd EG was called to the scene and accounted for "U-504" with "Kite", "Woodpecker", "Wren" and "Wild Goose".

Monthly Loss Summary
- 29 ships British, Allied and neutral ships of 188,000 tons in the Atlantic from all causes
- 34 U-boats including 3 by RAF and US aircraft off Portugal; 7 by US escort carrier groups south and west of the Azores (6 of these by aircraft from "Core", "Santee" or "Bogue"); 9 by US aircraft in the Caribbean and off Brazil.

Mediterranean

Invasion of Sicily: Operation 'Husky' - Axis submarines had fewer successes than the attacking aircraft in and around Sicily. Two British cruisers were damaged, but in return 12 of their number were lost over the four weeks into early August, including a number of Germans:

12th - "U-561" torpedoed in the Strait of Messina by MTB-81 and "U-409" sunk off Algeria by escorting destroyer "Inconstant" as she attacked a returning empty convoy.

23rd - Cruiser "Newfoundland" was damaged off Syracuse by a torpedo from "U-407".

30th - "U-375" was lost off southern Sicily to an American sub-chaser.

AUGUST 1943

Atlantic

Early August - "U-647" on passage out may had been lost on the Iceland/ Faeroes mine barrage around the 3rd of the month. If so she was the only casualty of this vast minefield throughout the war. RCAF aircraft sank "U-489" in the same area.

11th - "U-468" was sunk off Dakar, West Africa by a RAF Liberator of No 200 Squadron. The final attack was carried out with the aircraft in flames and just before she crashed. The Liberator's commanding officer, Plt Off Lloyd Trigg RNZAF, was posthumously awarded the Victoria Cross, solely on the evidence of the U-boat's survivors.

25th - "U-523" attacked UK/Gibraltar convoy OG92 to the far west of Cape Finisterre, Spain and was sunk by destroyer "Wanderer" and corvette "Wallflower". Bay of Biscay air patrols sank five U-boats in August and continued to co-operate with surface ships.

30th - In attacks on Sierra Leone/UK convoy SL135 northeast of the Azores, "U-634" was sunk by sloop "Stork" and corvette "Stonecrop".

Monthly Loss Summary
- 4 British, Allied and neutral ships of 25,000 tons, 1 escort
- 20 U-boats including 6 by aircraft of US escort carriers Card and Core off the Azores and in mid-Atlantic; 2 by US aircraft in the Caribbean area; 1 by RAF and French aircraft off Dakar; 1 by US forces in the South Atlantic

Mediterranean

22nd - Escort destroyers "Easton" and Greek "Pindos" sank "U-458" southeast of Pantelleria.

Monthly Loss Summary
11 British or Allied merchant ships of 43,000 tons

Indian Ocean

Merchant Shipping War - As Axis submarines continued to took a toll of Indian Ocean shipping (7 merchant ships of 46,000 tons in August) German "U-197" was sunk by RAF aircraft off Madagascar on the 20th, the first of two lost in the Indian Ocean in 1943.

SEPTEMBER 1943

Atlantic

Assault on the Escorts: Convoys ONS18 and ON202 - The German wolf-packs returned to the North Atlantic armed with Gnat acoustic torpedoes to home on and disable the escorts so they could reach the merchantmen. Adm Doenitz established a patrol line of 19 U-boats southwest of Iceland ready for UK-out convoys ONS18 (27 ships escorted by the British B3 group) and ON202 (42 ships and Canadian C2 group), which set out separately. First blood went to the RCAF on the 19th when "U-347" was sent to the bottom. Over the next three days six merchant ships were lost and the escorts suffered badly in the Gnat attacks. Two more U-boats were also sunk: 20th - British frigate "Lagan" of C2 was damaged by "U-270" or "U-260", but shortly after "U-338" was sunk by a VLR aircraft of RAF No 120 Squadron using the Allies' own acoustic torpedo - 'Fido'. "LAGAN" was towed home as a constructive total loss. The two convoys joined up southeast of Greenland and the escort reinforced by the Canadian 9th EG. 20th - Canadian destroyer "ST CROIX" (ex-US) of the 9th EG was lost to an attack by "U-305" and British corvette "POLYANTHUS" of C2 was hit by a Gnat, probably from "U-952" or possibly "U-641". 22nd - Destroyer "Keppel" of B3 sank "U-229", by which time the convoys were south of Cape Farewell, Greenland. By now frigate "ITCHEN" of the 9th EG had on board most of the survivors of "St Croix" and "Polyanthus". Around midnight she too was hit, in all likelihood by "U-666" and went down taking all but three men of the three ships' companies with her. (Note: "U-952" or "U-260" might also had been responsible for "ltchen's" loss.) Fortunately the Allies had anticipated the introduction of acoustic torpedoes and soon put into service 'Foxer' noisemakers, towed astern to attract the Gnat away from the vessel. The U-boats did not repeat their successes.

Monthly Loss Summary
- 11 ships of 54,000 tons and 4 escorts
- 6 U-boats including one each by RAF and RCAF Bay of Biscay patrols, and one by US aircraft off Brazil

Mediterranean

Italy - Surrendered on the 3rd, Salerno Invasion on the 9th

6th - On passage to Oran, escort destroyer "PUCKERIDGE" was sunk just east of Gibraltar by "U-617", herself lost six days later.

12th - Six days after sinking "Puckeridge", "U-617" was damaged by a RAF Wellington of No 179 Squadron and beached on the coast of Spanish Morocco. She was destroyed by gunfire from trawler "Haarlem", supported by corvette "Hyacinth" and Australian minesweeper "Wollongong".

OCTOBER 1943

Atlantic

8th - In attacks on Halifax/UK convoy SC143, "U-610" or "U-378" sank Polish destroyer "ORKAN" (ex-"Myrmidon") with an acoustic torpedo. Later in the day RAF and RCAF air escorts sank "U-419", "U-643" and "U-610".

Attacks on Convoys ON206 and ONS20 - Six U-boats were lost in exchange for a single merchantman in attacks on UK-out convoys ON206 (B6 group) and ONS20 (4th Escort Group). The 4th EG was mainly composed of the new US lease-lend 'Captain' class frigates. The B7 group commanded by Cdr Gretton first of all reinforced ON206. On the 16th, southeast of Greenland, RAF Liberators accounted for "U-470", "U-844" and "U-964". Next day on the 17th it was "U-540's" turn. Shortly after, as B7 transferred to ONS20, corvette "Sunflower" sank "U-631" with her Hedgehog. Still on the 17th, frigate "Byard" with the 4th EG escorting ONS20 sank "U-841". Cdr Gretton then took B7 to support nearby ON207.

Attacks on Convoys ON207 and ON208 - South of Iceland, B7 reinforced ON207's already formidable escort consisting of the Canadian C1 group and Capt Walker's 2nd EG. On the 23rd a RAF Liberator of No 224 Squadron and B7 destroyers "Duncan" and "Vidette" shared in the sinking of "U-274". Three days later the RCAF got "U-420". Then on the 29th, by now with ON208, B7 ships "Duncan", "Vidette" and Sunflower" sank "U-282". In less then two weeks in attacks on just four convoys, nine U-boats had been sunk by the highly efficient inter-service air and sea escorts.

31st - Northeast of the Azores, destroyer "Whitehall" and corvette "Geranium" of the British B1 group escorting North and West Africa/UK convoys MKS28 and SL138 detected "U-306" by HF/DF and sent her to the bottom.

Battle of the Atlantic - After lengthy negotiations ending in August 1943, Portugal granted the Allies the right to establish air and sea bases in the Azores as from October. This greatly extended the Allies' ability to cover the central Atlantic and the convoy routes between Britain and North and West Africa; also between North America and the Mediterranean.

Monthly Loss Summary
- 13 ships of 61,000 tons and 1 destroyer
- 23 U-boats including 4 by RAF and US aircraft in North Atlantic and off Portugal; 6 by US escort carriers Card, Core and Block Island off the Azores and in mid-Atlantic.

Mediterranean

30th - Submarine "Ultimatum" on patrol off Toulon, south of France sank "U-431".

31st - Five German U-boats set out for the Mediterranean, but one was sunk by the RAF while still in the Atlantic and two were disposed of by Gibraltar air and sea patrols. On the 31st destroyer "Douglas" and trawlers "Imperialist" and "Loch Oskaig" sank "U-732" off Tangiers. The second sinking was on the first day of November.

Indian Ocean

Merchant Shipping War - RAF aircraft sank their second U-boat of 1943 in the Indian Ocean with "U-533" on the 16th in the Gulf of Oman.

NOVEMBER 1943

Atlantic

6th - Capt Walker's Escort Group with escort carrier "Tracker" patrolled east of Newfoundland in support of convoy HX264. "U-226" was sighted by "Tracker's" aircraft and destroyed by sloops "Starling", "Kite" and "Woodcock". Shortly after, "Starling" this time with "Wild Goose", accounted for "U-842".

Attacks on the UK/ North and West Africa Convoy Routes - Combined UK-bound convoys MKS30 and SL139 were escorted by the 40th Escort Group and joined in turn by the 7th, 5th and 4th EG's to the far west and northwest of Portugal. One merchantman was lost to air attack, but three U-boats went down in the fighting: 19th - "U-211" to a RAF Wellington. 20th - Frigate "Nene" and Canadian corvettes "Calgary" and "Snowberry" of the 5th EG sank "U-536". 21st - Frigate "Foley" and sloop "Crane" of the 40th EG accounted for "U-538". Northwest of Cape Finisterre, Hs293 glider bombs sank the one merchant ship lost. The surviving U-boats were next deployed against other convoys in the area. As the U-boats approached southbound convoys KMS30/0S59 they ran into the 4th EG, which had also been diverted: 23rd - Frigates "Bazely", "Blackwood" and "Drury" sank "U-648". 25th - Two days later "Bazely" and "Blackwood" sank "U-600". Later, in the same area around the Azores, a RAF Wellington accounted for "U-542", and aircraft from US escort carrier "Bogue" the "U-86".

Monthly Loss Summary
- 7 ships of 28,000 tons and 1 US destroyer off the Azores
- 16 U-boats including 2 by RAF and US Bay of Biscay air patrols; 2 by RAF in North Atlantic and off the Azores; 3 by US forces in mid-Atlantic and off Ascension in the South Atlantic.

Mediterranean

1st - The second U-boat lost to the Strait of Gibraltar defences following the sinking the day before was "U-340" to destroyers "Active" and "Witherington", sloop "Fleetwood" and RAF aircraft of No 179 Squadron.

Mid-November - Submarine "SIMOOM" sailed from Port Said on the 2nd for the Aegean and failed to answer a signal on the 19th. She was presumed mined although German records claim she was torpedoed by "U-565" off Kos on the 15th.

28th - On passage through the Mediterranean to join the Eastern Fleet, cruiser "Birmingham" was badly damaged northwest of Derna by "U-407".

DECEMBER 1943

Atlantic

24th - Destroyer "HURRICANE" of the 1st EG with UK/African convoys OS62 and KMS36 was torpedoed by "U-305" or "U-415" northeast of the Azores, and scuttled next day.

Monthly Loss Summary
- 7 ships of 48,000 tons and 2 destroyers including one US in the North Atlantic
- 5 U-boats including 1 by RAF Bay of Biscay patrol; 3 by US Navy in Azores and Madeira areas; 1 scuttled after storm damaged in mid-Atlantic.

Mediterranean

U-boats attacks on UK/North Africa Convoy KMS34 - U-boat attacks were made on the Convoy off the Algerian coast using acoustic torpedoes: 11th - "U-223" damaged frigate "Cuckmere". 12th - Northeast of Bougie, "U-593" sank 'Hunt' escort destroyer "TYNEDALE". A long hunt ensued by escort destroyers "Calpe" and "Holcombe" and US destroyers "Benson", "Niblack" and "Wainwright", in the course of which the U-boat managed to sink "HOLCOMBE". 13th - After more than 30 hours the escorts finally sent "U-593" to the bottom. Other US destroyers including "Niblack" sank "U-73" on the 16th. This was the 23rd U-boat lost in the Mediterranean in 1943.