'HG' was the designation of Allied slow and fast convoys (together with a numerical) plying from Gibraltar or, in the case of three of the convoys, Port Said to Liverpool in the UK, and as such reciprocals of the 'OG' series (September 1939/September 1942).

The ships of these 'Homeward from Gibraltar' convoys from Gibraltar were included in 'MK' convoys, and after 'Torch' the HG convoy series was replaced the 'MKS' series. The first of the 117 such convoys, which included several composed only of faster ships and therefore had their primary designations suffixed with the letter F, was HG.1 of 26 September/6 October 1939 with 28 merchant vessels and eight escorts, and the last was HG.89 of 19/30 September 1942 with 19 merchant vessels and eight escorts.

The most significant of the 'HG' convoys was HG.76, for in the course of its passage between 14 and 30 December 1941 it lost four of its own number but also sank four U-boats and is thus seen as the first major British victory in the Battle of the Atlantic. The HG.76 convoy comprised 32 ships either in ballast or carrying trade goods. The escort was notably strong, eventually including 24 warships, and was centred on Captain F. J. Walker’s 36^th Escort Group with the sloops Stork and Deptford, and the corvettes Convolvulus, Gardenia, Marigold, Penstemon, Rhododendron, Samphire and Vetch; these were further bolstered by the new escort carrier Audacity and her three escorting destroyers Blanckney, Exmoor and Stanley together with the sloops Black Swan and Fowey, and corvettes Carnation and Free French Malouine.

Facing the convoy and the 17 warships of its escort were the 'Seeräuber' (i) wolfpack (U-67, U-107, U-108, U-131, U-434 and U-574), later reinforced by another three boats.

The convoy’s departure was reported almost immediately by German agents across Algeciras Bay in neutral Spain, who were able to report the convoy’s composition, escort strength and departure time. The convoy was also sighted later that day by U-74, which was on its way to the Mediterranean, but was then lost in poor visibility, while Vizeadmiral Karl Dönitz, the Befehlshaber der Unterseeboote, was temporarily confused by an agent’s report that the convoy had returned to port. The wolfpack was disposed in a patrol line in an area to the south of Cape St Vincent, but the convoy passed through the line without detection.

Meanwhile Korvettenkapitän Bruno Hansmann’s U-127 was detected during a routine anti-submarine sweep by a group of four destroyers from Gibraltar, and after a brief attack was sunk by the Australian destroyer Nestor.

On 16 December the convoy was sighted and reported by a Focke-Wulf Fw 200 Condor long-range maritime reconnaissance aeroplane patrolling from Bordeaux-Mérignac, and following this report U-108 gained contact and shadowed the convoy as the rest of the wolfpack closed during the night of 16/17 December. By daybreak on 17 December four boats were in contact. However, the combination of vigorous patrolling by the escorts and aircraft from Audacity led to the detection of Korvettenkapitän Arend Baumann’s U-131, which was attacked by Stork, Penstemon and the three destroyers. U-131 was driven to the surface and then sunk, though not before shooting down one of Audacity's Grumman Wildcat fighters.

During the night of 17/18 December the wolfpack attacked again, but the aggression of the escorts prevented them from achieving any hits, and at dawn on 18 December Korvettenkapitän Wolfgang Heyda’s U-434 was sighted by the destroyers, and then attacked, rammed and sunk by Blankney, which was damaged in the process. During the rest of the day several of the escorts had to leave: the sloops Black Swan and Fowey and the corvettes Carnation and Malouine returned to Gibraltar to refuel, while Blankney departed for repairs, escorted by Exmoor.

During the night of 18/19 December Stanley sighted Oberleutnant Dietrich Gengelbach’s U-574 as it shadowed the convoy, attacked but was herself torpedoed and sunk. Samphire and Stork responded and destroyed U-574, picking up survivors from both the destroyer and U-boat. Also during the night Korvettenkapitän Klaus Scholtz’s U-108 attacked successfully, torpedoing the 2,869-ton British Ruckinge, which was abandoned and sunk later by Samphire.

On 19 December the convoy was attacked by a force of Condor warplanes, which caused no damage but lost two of their number shot down and another damaged by Wildcat fighters from Audacity. On the same day the surviving boats of the wolfpack were informed that they were to be supplemented by three more boats from Bordeaux in the form of U-71, U-567 (captained by the 'ace' Kapitänleutnant Engelbert Endrass) and U-751, despatched on this day and arriving on 21 December.

During the next three days the wolfpack’s three surviving boats (U-67, U-107 and U-108) continued to shadow and on occasion attacked without success. Swelled to six in number on 21 December, the U-boats again prepared to attack. Walker attempted to draw off the attack by having Deptford make a demonstration some distance way from the convoy: this effort was unsuccessful, for some of the merchant ships were confused by the display, and also fired star shells, thereby revealing their position. Endrass’s U-567 sank the 3,324-ton Norwegian Annavore, while Kapitänleutnant Gerhard Bigalk’s U-751 sighted Audacity, zig-zagging behind the convoy without her escort. Bigalk fired, and Audacity succumbed to the hits of three torpedoes. Marigold, Samphire and Vetch counterattacked, but without result.

Later that night Deptford spotted a U-boat on the surface, attacked with depth charges, but seemed to gain no result, though post-war analysis revealed that she had sunk Endrass’s U-567. Following this, Deptford collided with Stork, both warships being damaged.

On 22 December U-71 and U-751 remained in contact, to be joined by U-125, which was on passage to the hunting grounds off North America, and the convoy was reinforced by the destroyers Vanquisher and Witch. On 23 December Dönitz called off the attack, and U-67, U-107, U-108 and U-751 broke way to return to bases in occupied France.

In overall terms, therefore, the loss of Audacity and three other ships was more than counterbalanced by the safe arrival of 30 ships and the destruction of three U-boats ( U-127 was not included and U-567 not confirmed until after the war). The convoy victory also confirmed Walker as the leading British exponent of anti-submarine warfare. Dönitz and the U-boat arm were severely shaken by their losses, particularly that of Endrass, who was the leading U-boat 'ace' at that time.