Convoys ONS 20/ON 206

ONS 20 and ON 206 were North Atlantic convoys of the ONS/ON series which ran during the battle of the Atlantic in World War II. They were the subject of a major U-boat attack in October 1943, the third battle in the German Navy’s Kriegsmarine KM’s autumn offensive.

Background
Despite the losses suffered by Rossbach and poor results achieved during its attack on SC 143. Still believing their new weapons and tactics gave them an advantage, BdU(Befehlshaber der Unterseeboote, Commander of the Submarines) re-organized the boats then in the North Atlantic into patrol line Schlieffen with the intention of intercepting the expected west-bound convoys. These were ONS 20 and ON 206.

Ships involved
ONS 20 departed Liverpool on 9 October 1943. Composed of 52 ships it was bound for Halifax, and was escorted by B-4 escort group, which comprised 6 destroyer escorts led by HMS Bentinck (Cdr HR Paramor as Senior Officer Escort).

ON 206 departed Liverpool on 11 October 1943; Composed of 62 ships, mainly in ballast, it was bound for New York  and was  escorted by B-6 escort group, comprising 2 destroyers, Fame (Cdr RA Currie SOE) and Vanquisher, the frigate Deveron, and 3 corvettes.

Also in the vicinity was Escort group B-7, in the role of a support group; it comprised 2 destroyers, Duncan (Cdr P Gretton) and Vidette, and 4 corvettes.

Group Schlieffen comprised a number of U-boats from group Rossbach, re-inforced by new-comers from bases in France and Germany. It had already come under attack whilst re-fueling by aircraft from USS Card; one boat was damaged and forced to retire, and 2 boats (U-402 and U-603 ) had been sunk. Another 2 boats had collided, and one of these was also forced to return to base for repair. At the time of the attack on convoys Schlieffen consisted of 14 boats, with a mix of experience and type.

When Allied intelligence learned of the position of Schlieffen, Western Approaches Command decided to seek battle, increasing  the defence by joining the two convoys and their escorts, and sending B-7 as reinforcement.

Action
On 15 October 1943 the convoys were sighted by U-844, and group Schlieffen was direct to converge on the position.

By evening a number of boats were in position and commenced the attack, which became one of the most calamitous of the entire campaign  for the U-boat Arm (U-Bootwaffe,UBW).

During the night of 15/16 October the U-boats attacked but were repelled; U-844 was damaged by Duncan and Vanquisher and driven off.

Later on 16 October U-844 was attacked and sunk by two Liberators, from RAF 86 and 59 squadrons; one Liberator was shot down, but the crew rescued by the corvette Pink. Also on 16th U-964 was sunk by a Liberator of RAF 86; her survivors were later picked up by U-231. Early that day U-470 was damaged by a Sunderland of RCAF 422 sqdn; the Sunderland was also damaged, ditching later near the ships of ONS-20 and its crew rescued by HMS Drury. Later, U-470 was attacked again, by 2 Liberators from RAF 120 and another from RAF 59, and sunk; 2 of her crew only were picked up by Duncan. The only success for the Schlieffen boats that day was when U-426 sank the freighter Essex Lance, which was straggling from  ONS-20.

During the night of 16/17 October the attack was renewed, but repelled with no success; U-540 was attacked and damaged by a Liberator of 59 sqdn; later that day she was attacked again and sunk by 2 Liberators from RAFs 59 and 120. Also on 17 October U-841 was sunk by Byard of B-4 group.

During the night of 17th/18th the shadower U-631 was sunk by Sunflower of B-7 group. At this point the convoys made a drastic alteration in course, in order to shake off any shadowers; this was successful in that BdU received two conflicting reports from U-91 and U-413, leading to Schlieffen being sent in the wrong direction.

After pursuit was shaking off, Schlieffen was unable to re-gain contact, and in view of the losses sustained BdU ordered the group to retire.

On 20 October, with no further attack developing, B-7 Group detached from the convoys to join ON 207, which was following; ONS 20 was handed over to its Western Local Escort Group on 22 October, and arrived at Halifax without further loss on 26 October 1943. ON 206 met its Local Escort Group on 24 October and arrived at New York on 27 October 1943.

Conclusion
BdU regarded this operation as a setback, but remained confident that their new weapons and tactics would achieve success. However the loss of 6 U-boats for the sinking of just one ship was a major defeat for the UbW and seen as a victory for the Allies.

Tables
Allied ships sunk

Axis submarines destroyed

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