This was a U-boat wolfpack operation in the Atlantic against the ONS.136 and ONS.137 convoys (6/20 October 1942).
The wolfpack comprised U-71, U-84, U-89, U-132, U-183, U-254, U-260, U-301, U-353, U-381, U-382, U-402, U-437, U-438, U-441, U-442, U-443, U-454, U-518, U-563, U-571, U-575, U-597, U-602, U-609, U-610, U-620, U-621, U-658, U-662, U-704, U-706, U-753 and U-757, and for the loss of Korvettenkapitän Eberhard Bopst’s U-597, which was sunk on 12 October to the south-west of Iceland by a depth-charge attack of a Consolidated Liberator long-range patrol aeroplane of the British No. 120 Squadron, sank three ships (16,081 tons).
On 11 October U-620 sighted the ONS.136 convoy of 36 ships supported by the British Escort Group B3, and the boat’s report elicited the detachment of U-254, U-353, U-382, U-437, U-442, U-597, U-620 and U-662 to attack it as the ‘Leopard’ (i) wolfpack. On 16 October, in the southern half of the ‘Panther’ (iii) wolfpack’s patrol line, U-704 spotted the ON.137 convoy of 40 ships supported by Lieutenant Commander D. W. Piers’s Canadian Escort Group C4 (HF/DF-equipped destroyers Restigouche and St Croix, corvettes Amherst, Arvida, Orillia and British Celandine, and HF/DF-equipped rescue ship Bury). U-71, U-84, U-89, U-132, U-381, U-402, U-438, U-454, U-571, U-609 and U-658 of the ‘Panther’ (iii) wolfpack and U-216, U-258, U-356, U-410, U-437, U-442, U-599, U-615, U-618 and U-662 of the ‘Wotan’ (ii) wolfpack, earlier in pursuit of the SC.104 convoy, were instructed to group and attack. In conditions of bad visibility, U-609 encountered Celandine while trying to attack, dived and was then depth-charged, but managed to escape.
In a westerly wind the U-boats were unable to reach the convoy on 17/18 October. The ‘Wotan’ (ii) wolfpack’s boats had to return to base from 18 October, and next day the operation was terminated.
The ‘Panther’ (iii) wolfpack’s boats now moved either to refuel from U-463 or to reach the new ‘Veilchen’ (i) wolfpack patrol line to the north of Newfoundland. On their way the boats encountered some independent sailers: Kapitänleutnant Walter Freiherr von Freyberg-Eisenberg-Allmendingen’s U-610 sank the 5,718-ton US Steel Navigator, Kapitänleutnant Ralph Kapitzky’s U-615 the 12,656-ton British Empire Star, and Kapitänleutnant Kurt Baberg’s U-618 the 4,772-ton US Angelina.