Convoy OB 318

Convoy OB 318
Part of World War II
Date 7–10 May 1941
Location North Atlantic
Result British Victory
Belligerents
Germany United Kingdom
Commanders and leaders
Admiral Karl Dönitz Convoy Comm: WB MacKenzie RNR
Escort : Cdr AJB Baker-Cresswell
Strength
4 U-Boats 40 ships
8 escorts
Casualties and losses
1 U-boat captured
2 U-boats damaged		 7 ships sunk (35,315GRT)
2 damaged

OB 318 was a North Atlantic convoy which ran during the Battle of the Atlantic in World War II. It saw the capture of U-110 and a wealth of signals intelligence, which led to the Allied breakthough into cracking the German naval Enigma code.

Contents

Prelude

OB 318 was a west-bound convoy of 38 ships, either in ballast or carrying trade goods, and sailed from Liverpool on 2 May 1941 bound for ports in North America. The convoy commodore was R.Adm. WB MacKenzie in SS Colonial.[1] It was escorted by 7 EG, an escort group led by HMS Westcott (Cdr. Bockett-Pugh) and comprising ten warships; these were joined in md-ocean by 3 EG, a force of eight warships led by HMS Bulldog (Cdr J Baker-Cresswell). Opposing them was a force of nineteen U-boats, though in the event only six were in a postion to pose a threat.[2]

Action

OB 318 was sighted on 7 May 1941 by U-94, which reported its position and commenced shadowing while U-boat Command (BdU) alerted other U-boats in the area. There were six U-boats witin striking distance, and these were ordered to close with U-94's position. Meanwhile during 7 May the escort force was joined by five ships from Iceland and the destroyers of 3 EG, which were to take over escort duties from the Western Approaches to a dispersal point at 34 West, a location south of Greenland. Three ships and the destroyers of 7 EG left for Iceland during 7 May, leaving the escort force still at ten warships.[3]

At nightfall on 7 May U-94 attacked the convoy, sinking two ships. Her skipper, Herbert Kuppisch, was able to enter the convoy by submerging ahead of the convoy and letting the lead escorts pass. he was then able to fire at close range on the ships in the centre of the convoy, hitting Ixion and Eastern Star. However U-94 was found by the sloop Rochester and counter-attacked by her, Bulldog and Amazon for four hours. U-94 was damaged and forced to retire, though she was able to effect repairs later and continue her patrol.

On 8 May the remaining vessels of 3 EG, three corvettes and two trawlers, with the Armed Merchant Cruiser Ranpura in company, joined the convoy, and the remaining ships of 7 EG departed.

On the evening of 8 May U-110 and U-201 also made contact, tracking the convoy until morning. In an unusual move, the two skippers made rendezvous in order to co-ordinate their attack; Fritz-Julius Lemp in U-110 would make a submerged attack from ahead, while Adalbert Schnee in U-201 would do the same from the rear. It was expected that the escort would have departed by this time, leaving the convoy vulnerable to their assault.[4]

During the morning of 9 May U-110 moved into position and commenced her attack. Lemp was surprised to encounter the escort still in place, but succeeded in penetrating the convoy, sinking two ships. U-110 was also vigorously counter-attacked, by Aubretia, Bulldog and Broadway. She was forced to the surface and abandoned. U-110 was still afloat and was captured by the three warships, which dropped out of the convoy to secure their prize.[5]

Meanwhile Schnee in U-210 made his attack, sinking one ship and damaging another. He was also counter-attacked, by Amazon, Nigella and St Apollo, and forced to retire, damaged.[6]

In the ealy hours of 10 May OB 318 was found by U-556 which attacked immediately, resulting in one ship damaged. As OB 318 was at its dispersal point, the convoy separated during the night, while the escorts departed to meet their next charge. However U-556 was able to keep in touch with a group of ships heading south-west, and during the day sank two more.[7]

Over the next two weeks the remaining 36 ships from OB 318 made landfall at various ports around the Atlantic, although three, including the convoy commodore's ship Colonial, were sunk before arriving by U-boats patrolling near their destinations.

Aftermath

The action around OB 318 was a qualified Allied success. Five ships were lost in attacks on the convoy,and two more shortly after dispersal. In reply, one U-boat was lost and two damaged, a poor rate of exchange and one which illustrated the growing effectiveness of the escort forces. Thirty-three ships arrived safely at their destinations.

However outweighing the material losses in this action was the capture, intact, of U-110 and her signal equipment, including an Enigma coding machine, current rotors and code-books. Though U-110 was subsequently lost, sinking while under tow, the signals intelligence was invaluable to the Allied code-breakers at Bletchley Park, and led to a lasting break-through in reading German naval traffic (with some interruptions) throughout the rest of the Atlantic campaign.

Tables

Allied ships hit

Date Name Nationality Casualties Tonnage (GRT) Sunk by...
7 May 1941 Ixion Br none 10,263 U-94
7 May 1941 Eastern Star Nor none 5,658 U-94
9 May 1941 Bengore Head Br 1 2,609 U-110
9 May 1941 Esmond Br none 4,976 U-110
9 May 1941 Gregalia Br none 5,802 U-201
9 May 1941 Empire Cloud Br none damaged U-201
10 May 1941 Aelybryn Br none damaged U-556
10 May 1941 Empire Caribou Br 38 4,861 U-556
10 May 1941 Gand Bel 1 5,086 U-556

U-boats hit

Date Number Type Commander Casualties Hit by...
7/8 May 1941 U-94 VIIC K/L H. Kuppisch  ? damaged
9 May 1941 U-110[8] IXB KK. F-J Lemp 15 Aubretia, Bulldog, Broadway
9 May 1941 U-201 VIIC O/L A. Schnee  ? damaged

Notes

  1. ^ Hague
  2. ^ Blair p278
  3. ^ Blair p278
  4. ^ Blair p279
  5. ^ Kemp p70
  6. ^ Blair p281
  7. ^ Blair p283
  8. ^ Niestle p120

References

External links