Operation Substance was a British naval operation in July 1941 during the Second World War to escort Convoy GM 1 from Gibraltar to Malta and Convoy MG 1 from Malta. Italian submarines, aircraft and MAS boats (Motoscafo armato silurante, motor torpedo boats) attacked the ships.
In the spring of 1941, the strategic situation in the Mediterranean had deteriorated. The Axis armies in Libya forced back the British to the Egyptian frontier; German armies had overrun Jugoslavia and then captured Greece and Crete, causing severe losses to the Mediterranean Fleet. Force H, in the western Mediterranean, was still intact and supply convoys to Malta would have to come from the west.
Convoy GM 1 of six merchant ships and a troop transport was to be escorted to Malta and Convoy MG 1 of seven unloaded freighters escorted from Malta to Gibraltar. Force H was to take the Malta convoy as far as the Sicily–Tunisia narrows, reinforced by Force X that had escorted the ships from Britain to Gibraltar. the Force x cruisers and destroyers would take the convoy through to Malta, as the reciprocal Convoy MG 1 sailed, Force H cruising near Sardinia in wait for both.
The destroyer HMS Fearless was hit by a torpedo bomber and scuttled, the cruiser HMS Manchester was torpedoed, damaged and towed back to Gibraltar, HMS Firedrake was near-missed and damaged by bombers. The merchant ship Sydney Star in Convoy GM 1 was torpedoed by a MAS boat and Hoegh Hood in Convoy MG 1 was hit and damaged by a torpedo bomber; twelve Fulmar fighters of HMS Ark Royal were shot down and nine Italian aircraft were claimed and several damaged.
Background
British plan
Supply runs to Malta by submarine were known as Magic Carpet runs, that in July 1941 carried 84,280 imp gal (383,100 L; 101,220 US gal) of petrol, 83,000 imp gal (380,000 L; 100,000 US gal) of paraffin, 6 long tons (6.1 t) of aircraft ammunition, torpedoes and other munitions, 30 long tons (30 t) of stores, 136 service personnel and 12 long tons (12 t) of post yet submarine transport was far less preferable to bulk freight being delivered by ship.
After the Battle of Crete (20 May – 1 June 1941) Admiral Andrew Cunningham, the Commander-in-Chief, Mediterranean Fleet, signalled Admiral of the Fleet, Sir Dudley Pound, the First Sea Lord, at the Admiralty, on 2 June, that with the Luftwaffe busy in the eastern Mediterranean it would be wise to send a convoy to Malta from the west. Fliegerkorps X had been transferred from Sicily to Poland for Operation Barbarossa, the invasion of the Soviet Union.
The unladen ships at Malta from earlier supply convoys would depart as Convoy MG 1 to take advantage of Forces H and X. The convoy would sail in three groups determined by ship speed, the HMS Breconshire a civilian ship converted to a fast tanker and Talabot group would sail at 17 kn (31 km/h; 20 mph), a second group, Thermopylæ and Amerika would sail at 14 kn (26 km/h; 16 mph) and the third group, Settler, Svenor and Hoegh Hood would make 12 kn (22 km/h; 14 mph) and be met by Force X from Malta and Force H south-west of Sardinia.
Mediterranean Fleet
In Operation ME 2, two submarines near Crete would send misleading signals to suggest that HMS Queen Elizabeth and its escorts were heading westwards and in Operation ME 3 the real ships would return to Alexandria under cover of night. The main effort would come from the west but eight submarines would patrol off Italian naval bases, in case the Italian fleet sortied. The British thought that the Italians had five operational battleships, three at Taranto and ten cruisers at Taranto, Messina and Palermo. Sending a convoy from Malta with only one destroyer escort was risky but with the Mediterranean Fleet so depleted, it could not be helped.
Royal Air Force
The Royal Air Force had more aircraft than in January and could provide anti-submarine sorties from Gibraltar for the first two days of the voyage east from Gibraltar and other aircraft could watch between Sardinia and north Africa and the Italian ports. Fighters on Malta could cover Force X after Ark Royal had turned back with Force H. Intelligence reported that German aircraft had left the western Mediterranean and that the Regia Aeronautica had about fifty torpedo bombers, 120 medium bombers and thirty dive bombers split roughly evenly between Sardinia and Sicily.
Axis
Axis air forces
Italuft, a Luftwaffe liaison headquarters had been established in Rome in June 1940 and Fliegerkorps X (General Hans Geisler) with about 120 bombers, 150 Junkers Ju 87 dive bombers, 40 Messerschmitt Bf 110 heavy fighters and twenty reconnaissance aircraft was in Sicily by mid-January 1941. Fliegerkorps X was to subdue Malta, to attack British ships, cut the Mediterranean supply route to Egypt and support the Axis army in Libya and it began attacks British ships at Malta on 9 January 1941. On 10 January the Luftwaffe attacked the ships of Operation Excess with 60 Junkers Ju 87 dive bombers and Heinkel He 111 medium bombers and inflicted severe damage on the aircraft carrier HMS Illustrious. on the following day two cruisers were damaged, one being scuttled. On 16 January attacks began on Illustrious in Grand Harbour at Malta, causing severe damage to the docks, houses, then the bombers turned to the airfields, bombing that continued until March. In May Fliegerkorps X was transferred to prepare for the invasions of Jugoslavia and Greece.
Prelude
Convoy WS 9c
On 27 June, in great secrecy, the reefer ship, SS Port Chalmers (8,535 gross register tons [GRT]) unloading New Zealand meat at Avonmouth, was requisitioned by the Ministry of War Transport and sent to Newport, where it took on cement, wheat, maize, corned beef, cigarettes, cloth, firearms, ammunition, vehicles, aircraft parts and 2,000 long tons (2,000 t) of cased petrol. Just before sailing, 250 gunners of the Royal Artillery with one light, one heavy anti-aircraft regiment and thirty field guns were embarked with a naval liaison officer. On deck, six 40 mm Bofors guns were fixed to the superstructure to go with the seven Lewis guns and the 4.7-inch gun on the poop deck already carried.
The ship sailed on 11 July, escorted by the Dutch destroyer leader HNLMS Jacob van Heemskerck and met MV Deucalion (7,740 GRT) en route to the Mersey. On 12 July SS Sydney Star (12, 696 GRT) and City of Pretoria (8,049 GRT) departed the Mersey with destroyer escorts and sailed parallel with Port Chalmers and Deucalion, none of the captains knowing who was the convoy commodore. Captain Thomas Horn of Sydney Star found that he was the commodore and ordered the ships into line abreast. During the morning of 13 July other ships joined from the Clyde, the ex-French SS Pasteur (29,253 GRT) MV Melbourne Star (12, 806 GRT) SS Avila Star (14,443 GRT), MV Durham (10,893) and the ferry MV Leinster (4,303 GRT).
The ships turned south for Gibraltar and the captain of Melbourne Star, David MacFarlane, took over as convoy commodore. The ships' masters were not told of the destination until Force X arrived. During the voyage south, Syfret exercised the merchant ships in simultaneous manoeuvring, that was useful when the steering gear on Manchester broke down and it veered towards Port Chalmers. The journey continued until Avila Star left the convoy, not being in the operation and on 20 July, nearing Gibraltar, HMAS Nestor delivered sealed orders to the merchant ships. During the remaining daylight the convoy exercised and then began the passage of the Strait of Gibraltar.
Force X
To escort the convoy to Gibraltar, the Home Fleet detached the battleship HMS Nelson (to join Force H) the cruisers HMS Edinburgh (flagship of Rear-Admiral Neville Syfret), Manchester and Arethusa, the fast minelaying cruiser HMS Manxman, the fleet destroyers HMS Cossack, Maori, Sikh, Lightning, Nestor and the Hunt-class destroyers HMS Avon Vale, Eridge and Farndale.
Force H
Force H comprised the aircraft carrier HMS Ark Royal with 27 Fulmars of 807 Naval Air Squadron (NAS) and 808 NAS. Seven Swordfish torpedo bombers, reinforcements to be delivered to Malta were also on Ark Royal. The battleship Nelson and the cruisers Edinburgh Manchester and Arethusa (joining from Force X) the battlecruiser HMS Renown, the fast minelayer Manxman and the destroyers HMS Duncan, Faulknor, Fearless, Foxhound, Firedrake, Foresight, Fury and Forester participated. Force S was composed of the oiler RFA Brown Ranger with the destroyer HMS Beverley.
The returning ships from Malta, Convoy MG 1 had the destroyer HMS Encounter as an escort. Submarines based at Alexandria were to participate by lying off Italian ports, ready to ambush the Regia Marina if it sailed.HMS Olympus and HNLMS O-21 patrolled off Naples, HMS Urge off Palermo, HMS Upholder off Marettimo (western Sicily) HMS P32 off Cagliari (southern Sardinia) HMS Utmost in the southern Tyrrhenian Sea, to the north of Messina (north-east Sicily) with HMS Unique and HMS Upright in the Strait of Messina.
Convoy GM 1
21 July
The convoy entered the Mediterranean through fog and squally weather. Each merchant ship streamed a fog buoy that sent up a water plume for the ship behind to follow. Visibility got so bad that the merchant ships turned on their navigation lights until they emerged from the fog and closed formation at 14 kn (26 km/h; 16 mph). Some of the ships put into Gibraltar and escorts docked to fuel and transfer troops. Around 3:30 a.m. on 21 July, Somerville ordered some of the ships in Gibraltar to sail, with the fog having lifted and the wind dropping. Leinster, carrying Royal Air Force (RAF) ground crews for Beaufighter units on Malta, sailed but went aground in a patch of fog off Carnero Point and it was left behind, there being no time to embark its passengers on another ship.
Pasteur had ended its voyage at Gibraltar and there were delays in embarking its troops on other ships, leading later to a sharp complaint from the Admiralty to the War Office for inefficiency. Convoy GM 1 the convoy to Malta comprised Melbourne Star, Sydney Star, City of Pretoria. Port Chalmers, Durham and Deucalion, intended to sail at 14 kn (26 km/h; 16 mph). The fuelling of destroyers and cruisers had gone well, with only the disorganisation of the transfers from Pasteur and the grounding of Leinster causing problems. About 5,500 army and RAF personnel were embarked on Manchester, Arethusa, Cossack, Maori and Sikh, that had put into Gibraltar to collect them; other personnel were aboard the merchant ships.
The weather was windy and foggy until well after dawn, that obstructed the assembly of the ships into cruising formation, off Gibraltar, under air cover from the local Sunderland flying boats. Ark Royal kept its Fulmars at readiness and its Swordfish torpedo bombers out of the air, to avoid advertising that it had sailed. No Italian submarines were discovered but two merchant ships were seen during the day. The oiler Brown Ranger was seen by the Sunderlands and reported as Leinster, causing confusion until the discrepancy was resolved. The reciprocal Convoy MG 1 from Malta also sailed with one destroyer as escort. During the afternoon, Force H passed Convoy GM 1 and diverged to the north-east, until about 30 nmi (56 km; 35 mi) away and slowed to 18 kn (33 km/h; 21 mph).
22 July
Reconnaissance aircraft from 69 Squadron at Malta were sent to observe the Italian fleet at Taranto, one Maryland shooting down a CANT Z.506 Airone (Heron) near Syracuse in the south-east of Sicily. Malta Blenheims and Swordfish continued to attack Italian convoys, the German ammunition ship Preussen being hit and blown up, that set a tanker, MV Brarena (6,996 GRT), on fire, that was later torpedoed twice, drifted onto the Kerkennah Bank and was abandoned. An Italian aircraft flew over Force H but not enough to see the convoy and Force X beyond. The destroyers of Force X spent the day refuelling from Brown Ranger in pairs, taking about ten hours; the oiler then turned about with Beverley and headed for Gibraltar. Force H turned back for two hours, closing the distance with the convoy, then turned east again at 2:00 p.m.
Aircraft were seen at a distance but Fulmars from Ark Royal failed to catch them because of high cloud. To keep radio silence, Somerville and Syfret passed messages via a Sunderland, using Morse code, that Force H would come closer to the convoy on the morrow. In the afternoon, radar picked up more aircraft but the Fulmars failed to find them again. As dusk fell, Hermione mistakenly directed the fighters onto a Catalina flying boat from Gibraltar, that was attacked and a gunner wounded. Force H launched paravanes (devices to explode mines harmlessly) and reversed course again for an hour and a half, the distance between the force and the convoy falling to 20 nmi (37 km; 23 mi). Just before midnight the Italian submarine Diaspro discharged a salvo of torpedoes.that were spotted by Nestor on the starboard side and the force evaded them with a starboard turn, four torpedoes exploding when their runs ended and one passed ahead of Nestor and one underneath. Nestor made three depth charge attacks but the submarine escaped with minor damage. During the evening, nine S.79sil of 283 Squadriglia, from Sardinia, made an abortive search for the convoy.