Convoy HG 73

Convoy HG 73 was a trade convoy of merchant ships during the Second World War. It was the 73rd of the numbered HG convoys Homeward bound to the British Isles from Gibraltar. The convoy departed Gibraltar on 17 September 1941 and was found on 18 September and was attacked over the next ten days. Nine ships were sunk from the convoy before the submarines exhausted their torpedo inventory on 28 September. Surviving ships reached Liverpool on 1 October.
Forces involved.
HG 73 comprised 25 ships homeward bound from Gibraltar, many in ballast, or carrying trade goods.
The convoy commodore was Rear admiral. K.E.L Creighton in the cargo liner "Avoceta" 
and the convoy was protected by a Western Approaches Command escort group. This consisted of the sloop HMS "Fowey" and eight corvettes, reinforced by the auxiliary anti-aircraft cruiser/Fighter catapult ship HMS "Springbank". The convoy escort was augmented during the first few days by the destroyers "Duncan", "Vimy" and "Farndale", and was reinforced at various times throughout the voyage as warships came and went.
Ranged against HG 73 was an "ad hoc" wolfpack of five U-boats ("U-124", "U-201", "U-203", "U-205", and "U-371"), in concert with a group of four Italian submarines ("Da Vinci", "Malaspina", "Morosini" and "Torelli") on patrol west of the Straits of Gibraltar. They were assisted by aircraft from "Kampfgeschwader" 40 (KG40), flying long-range Fw 200 Condors, based at Bordeaux.
Action.
HG 73 sailed from Gibraltar on 17 September 1941, and was reported almost immediately by German agents across the bay in neutral Spain; these were able to report the convoy's composition, escort strength and departure time.
The Condors from KG40 and the four Italian submarines (unbeknownst to "Befehlshaber der U-Boote]]" "U-boat Command" (BdU) one of these, "Malaspina", had already been destroyed the previous week) were ordered to search for the convoy, while three U-boats further north were deployed in a search patrol line across the convoy's probable route.
On 18 September a Condor sighted HG 73 off Cape St Vincent, but this was driven off by the Fulmar launched from "Springbank".
On 19 September the convoy was sighted again, first by "Morosini", and later by "U-371", though both lost contact; "Morosini" fell out of the pursuit with engine trouble, while "U-371", en route to the Mediterranean, was ordered to continue on her way.
On 20 September the destroyers "Duncan" and "Farndale" departed, but were replaced by destroyer "Wild Swan".
Also on 20 September "U-124" made contact, but this proved to be a southbound convoy, OG 74. Unaware of this, BdU ordered "U-201" to join her and over the next two days and nights both U-boats attacked OG 74, succeeding in sinking five ships, though both received damage and depleted their store of torpedoes.
Meanwhile, HG 73 was attacked by the Italian boats, though without success: On the night of 21/22 September "Vimy" made a promising attack on a contact, and was later credited with the destruction of "Malaspina", though it was later suggested this attack had been on "Torelli", which survived, but was badly damaged and forced to return to base.
On 22 September the two destroyers, "Vimy" and "Wild Swan", left the escort, replaced by destroyer "Highlander".
On 23 September "Da Vinci" made contact, and shadowed the convoy throughout the day, but was unable to make an attack.
On 24 September a Condor spotted the convoy and reported three ships on fire, though British records show no ships hit. BdU diverted two more U-boats ("U-203" and "U-205") to the attack from France; these arrived over the next two days .
On 25 September "U-124" made contact in heavy seas and fired on a ship identified as a cruiser; this may have been "Springbank", but no hits were achieved, and no attack was noticed by any Allied ship.
That night "U-203" joined, and both U-boats attacked, scoring several hits. Just after midnight "U-203" sank "Avoceta" and "Varengberg", but came under attack from the corvette "Larkspur".
A few hours later "U-124" sank "Cortes" and "Petrel". The coaster, "Lapwing", stopped to pick up survivors from these two ships, but was herself torpedoed just before dawn. Of the 109 men on these three ships only 18 men survived, reaching land after a two-week voyage in an open lifeboat.
On 26 September, "Highlander" departed from the escort, while "U-124" and "U-203" continued to shadow. "U-201" and "U-205" also joined, but during the day "U-205" was attacked by an Allied aircraft; she was damaged and forced to return to base.
During the night of 26/27 September the three U-boats in contact attacked again; just before midnight "U-124" sank Siremalm, while at 2am "U-201" torpedoed and sank "Cervantes" and torpedoed "Springbank". "Springbank"s survivors were taken off and "Jasmine" sank "Springbank" with gunfire rather than leave her as a hazard.
During 27 September the three boats continued to shadow, and that night "U-201" made a final attack, sinking "Margareta"; neither "U-124" nor "U-203" were able to attack again.
With this the pursuing U-boats were obliged to abandon the operation, and return to base to re-arm. HG 73 was left to continue without further incident, arriving at Liverpool on 1 October.
Aftermath.
Despite the best efforts of the escort force, of the 25 ships that departed Gibraltar nine were lost, and one escort vessel, making this the worst loss of any HG convoy, and one of the worst of the entire Atlantic campaign.
Of the 117 convoys of the HG series run during the three years between September 1939 and September 1942, thirteen (just over one in ten) were attacked: Of the 2994 ships conveyed, 55 (approximately one in twenty) were lost; 39 to attacks on convoys, such as this one, and a further 16 losses out of convoy.
The operation was a victory for the attacking forces, though the successes claimed were inflated considerably. The three U-boat commanders were credited with sinking 15 ships, of 91,000 GRT, while the three ships spotted sinking on 24 September were credited to "Malaspina", which had failed to return, and was thus unable to report otherwise. The actual tonnage of the nine ships sunk was 25,800 GRT; the discrepancy is attributable to the generally smaller coasters of the Gibraltar route being misidentified as larger, ocean-going freighters. 
It was, however, the high point of Axis success on the Gibraltar route; just two months later the losses incurred attacking HG 76 forced BdU to abandon operations here in favour of softer targets elsewhere.
Ships in the convoy.
Allied merchant ships.
A total of 25 merchant vessels joined the convoy in Gibraltar.
Convoy escorts.
A series of armed military ships escorted the convoy at various times during its journey.