'Rügen' (iv) was a U-boat wolfpack operation in the Atlantic against the TU.5 and ON.215 convoys (7/29 January 1944).
Following seven individually numbered and smaller 'Rügen' (iv) groups whose survivors were assembled into this larger grouping, the wolfpack comprised U-92, U-212, U-260, U-271, U-281, U-302, U-305, U-309, U-311, U-364, U-377, U-382, U-390, U-392, U-406, U-471, U-545, U-547, U-571, U-592, U-641, U-650, U-666, U-731, U-741, U-757, U-762, U-846, U-976, U-981 and U-984, and for the loss of Kapitänleutnant Rudolf Bahr’s U-305, Oberleutnant Gerhard Kluth’s U-377, Kapitänleutnant Horst Rendtel’s U-641 and Korvettenkapitän Friedrich Deetz’s U-757 sank no ship.
The boats of the 'Rügen' (iv) wolfpack and, from a time in the middle of January, the remaining boats of the 'Borkum' wolfpack (U-305, U-382, U-377 and U-641) and the newly arrived U-212, U-231, U-238, U-271, U-571 and U-592 now operated in an area of the Atlantic to the west of Ireland as individual boats and in a number of different concentrations.
On 8 January Deetz’s U-757 was sunk by the British frigate Bayntun of Lieutenant Commander L. P. Bourke’s 4th Support Group and the Canadian corvette Camrose of Lieutenant Commander L. R. Pavillard’s Canadian 5th Support Group, which were elements of the escort for the combined OS.64 and KMS.38 convoys. Various U-boats sighted ships and their escort groups during the next few days, but had no success. On 14 January U-382 was depth-charged and damaged by the US destroyers Buhner and Parrott. Kluth’s U-377 was lost on 15 January in an encounter with Captain H. F. Fick’s US escort group centred on the escort carrier Santee, probably through being struck by her own circling torpedo. On 17 January Bahr’s U-305 was sunk by the British destroyer Wanderer and frigate Glenarm.
During the evening of 17 January a Heinkel He 177 long-range maritime reconnaissance bomber sighted and reported the combined OS.65 and KMS.39 convoys, which were supported by Commander M. J. Evans’s British Escort Group B3, but of the U-boats directed to the scene, only Rendtel’s U-641 managed to approach, but was then sunk by the British corvette Violet.