This was a U-boat wolfpack operation in the Atlantic against the SC.95, ONS.122 and SC.100 convoys (11 August/22 September 1942).
The wolfpack comprised U-135, U-174, U-176, U-216, U-256, U-259, U-373, U-410, U-432, U-438, U-462, U-569, U-593, U-596, U-599, U-605, U-660, U-705 and U-755, and for the loss of Kapitänleutnant Karl-Horst Horn’s U-705 sank eight ships (32,983 tons including the US weather ship Muskeget).
Some of the boats had recently been in action against the SC.94 convoy and others were fresh arrivals in the area, and together with two later arrivals, U-135 and U-432, these were ordered to create a new patrol line designed to locate the SC.95 convoy, whose imminent appearance had been forecast by the B-Dienst.
On 15 August U-256 located and reported the convoy, which comprised 27 ships supported by Commander Paul R. Heineman’s US Escort Group A3 (US Coast Guard cutter Spencer, US destroyer Schenck, Canadian corvettes Bittersweet, Collingwood, Mayflower and Trillium, and British corvettes Snowflake and Wallflower), but then lost contact.
Attacks by U-256 and U-605 failed, but Horn’s U-705 sank the 3,279-ton US Balladier and on 16 August Kapitänleutnant Gunter Jahn’s U-596 despatched the 4,966-ton Swedish Suecia, a straggler from the SC.95 convoy.
On 22 August U-135 caught sight of the ONS.122 convoy, which Admiral Sir Max Horton, heading the Western Approaches Command, had routed to the south of the ‘Lohs’ wolfpack. The convoy of 36 ships was supported by Lieutenant Commander J. V. Waterhouse’s British Escort Group B6 (HF/DF-equipped destroyer Viscount, Free Norwegian corvettes Acanthus, Eglantine, Montbretia and Potentilla, and rescue ship Stockport). On 23 August U-135 and U-660 were located by HF/DF, and on the following day were driven off. Nine U-boats closed on the convoy during the night of 24/25 August. Kapitänleutnant Herbert-Viktor Schütze’s U-605 sank the 3,163-ton British Katvaldis and 5,017-ton British Sheaf Mount, but was then depth-charged and damaged by Eglantine. Kapitänleutnant Reiner Dierkson’s U-176 and Kapitänleutnant Rudolf Franzius’s U-438 soon attacked simultaneously, the former sinking the 7,454-ton British Empire Breeze and the latter the 1,598-ton Norwegian Trolla. The German effort was made especially difficult by a presence of a sea mist, and the U-boats soon lost contact.
Already suffering from depth-charge damage inflicted by Potentilla and Viscount, U-256 was heavily bombed on 31 August in the Bay of Biscay as it returned to base, and was out of action for more than a year. Horn’s U-705 was sunk in the Bay of Biscay on 3 September by an Armstrong Whitworth Whitley medium-range anti-submarine aeroplane of the RAF’s No. 77 Squadron.
The boats of the ‘Lohs’ wolfpack were meanwhile heading to the south to refuel from U-174 (three boats) and U-462 (U-135, U-176, U-373, U-432, U-569 and U-755). On 6 September, these latter established a new patrol line, and on 9 September Kapitänleutnant Walter Göing’s U-755 sank the 1,827-ton US weather ship Muskeget. From 13 September U-410, U-599 and U-259 joined the pack.
On 18 September, as a result of a decoded Allied message, the wolfpack located the SC.100 convoy of 24 ships supported by the US Escort Group A3 (US Coast Guard cutters Campbell and Spencer, and other ships including the Canadian corvettes Bittersweet, Mayflower, Rosthern, Trillium and, on transfer to ‘Torch’, Lunenburg and Weyburn, and British corvette Nasturtium). The convoy and its escorts skilfully managed to lose the German contact-keeper during 18 September.
Even so, on 19 September, and despite steadily deteriorating weather, individual boats were nonetheless able to close with the convoy. In order to try to find it again, the ‘Pfeil’ wolfpack, located to the south-east and comprising U-216, U-221, U-258, U-356, U-595, U-607, U-615 and U-617, was ordered to redeploy. U-569 and U-373 missed escort vessels as they closed during 20 September, but Jahn’s U-596 sank the 5,676-ton British Empire Hartebeeste. On 21 September a storm made combat operations impossible, and on the following day the Germans ended their operation.
On 23 September, however, all the boats within range were ordered to attack the RB.1 convoy, located by the ‘Vorwärts’ wolfpack, and the others closed on the SC.100 convoy. Kapitänleutnant Albrecht Brandi’s U-617 sank the 8,882-ton British Athelsultan during the night of 22/23 September, and in the course of the following day picked off a pair of stragglers, namely the 2,342-ton British Tennessee and 3,563-ton British Roumanie. Kapitänleutnant Heinz-Otto Schultze’s U-432 sank the 5,868-ton US Pennmar. Attacks by U-258, U-221 and U-755 failed.
On 25 September the Germans ended their attempts against the SC.100 convoy.