'Hinein' was a U-boat wolfpack operation in the Atlantic against the ON.221 convoy (26 January/3 February 1944).

The wolfpack comprised U-212, U-271, U-281, U-441, U-571, U-592, U-650 and U-764, and for the loss of Kapitänleutnant Curt Barleben’s U-271 and Oberleutnant Gustav Lüssow’s U-571 sank no ship.

German air reconnaissance between 20 and 22 January had been able to find neither the expected HX.275 and SC.151 convoys nor the westbound ON.220 convoy supported by the Canadian Escort Group C4. Then on 26 and 27 January Junkers Ju 290 long-range maritime reconnaissance aircraft of the Fernaufklärungsgruppe 5 on several occasions sighted and reported the combined OS.66/KMS.40 and ON.221 convoys, and Grossadmiral Karl Dönitz, commander-in-chief of the German navy and still in operational command of the U-boat arm via Konteradmiral Eberhard Godt, his deputy for U-boat operations, ordered the concentration of U-212, U-271, U-281, U-571, U-592 and U-650 as the 'Hinein' wolfpack, and U-283, U-308, U-386, U-390, U-466, U-545, U-547, U-666, U-731, U-762, U-984, U-985 and U-989 as the 'Stürmer' (ii) wolfpack against these convoys.

In support of the convoys, aircraft of Air Vice Marshal L. H. Slatter’s No.15 Group of Air Chief Marshal Sir William Sholto Douglas’s RAF Coastal Command, reinforced by aircraft of Air Vice Marshal B. E. Baker’s No. 19 Group of the same command, carried out a large-scale operation against the U-boat formations. U-571 and U-271 were sunk on 28 January by a Short Sunderland flying boat of the RAAF’s No. 461 Squadron and a Consolidated Liberator long-range maritime patrol bomber of the US Navy’s VP-103 squadron flying cover for the SC.151 and ON.221 convoys. On 29 January Oberleutnant Heinz Jaschke’s U-592 was damaged by a Liberator of the VP-102 squadron and while on passage back to France was sunk on 31 January by the sloops Starling, Wild Goose and Magpie of Captain F. J. Walker’s 2^nd Support Group. Also on its way back to France, Oberleutnant Paul-Heinrich Sass’s U-364 was lost to unknown causes in the Bay of Biscay some time on or after 29 January, the most probable cause being depth charges from a Handley Page Halifax patrol bomber of No. 502 Squadron. A Vickers Wellington medium-range maritime patrol bomber of the RAF’s No. 172 Squadron was shot down by U-608.

On 29 January the U-boats were all recalled to France because of a false invasion alarm and were then ordered to new positions.