Operation Substance

Operation Substance
Part of the Battle of the Mediterranean of the Second World War
Cloud of smoke over the Mediterranean Sea from a hit destroyer - possibly HMS Fearless. In the foreground is the battleship HMS Nelson.
Date 13–28 July 1941 Location Mediterranean Sea Result British victory
Belligerents
United Kingdom  Australia	Italy
Commanders and leaders
James Somerville
Strength
1 aircraft carrier 1 battleship 1 battlecruiser 4 light cruisers 18 destroyers 13 merchant ships	3 torpedo boats 1 submarine 4 MAS boats 9 torpedo bombers 4 medium bombers
Casualties and losses
1 destroyer sunk 1 light cruiser damaged 1 destroyer damaged 2 merchant ships damaged 6 aircraft 35 killed	12 aircraft

Operation Substance was a British naval operation in July 1941 during the Second World War to escort Convoy GM 1, the first of the series from Gibraltar to Malta.^[1] The convoy, escorted by Force H, was attacked by Italian submarines, aircraft and MAS boats (Motoscafo armato silurante, motor torpedo boats).

Port Chalmers carried 250 members of the Royal Artillery one light, one heavy anti-aircraft regiment and thirty field guns to strengthen the island against airborne assault.^[2] Medical personnel expected to be needed in the anticipated Siege of Malta were also embarked.^[3]

Force H included the battleship HMS Nelson, the battlecruiser HMS Renown, the fast minelayer HMS Manxman, the cruisers HMS Manchester, Edinburgh and Arethusa with eight destroyers and the aircraft carrier HMS Ark Royal with 21 Fairey Fulmar fighters and ferrying seven Fairey Swordfish reinforcements to Malta.^[2]

The Royal Navy observed a decrease in the intensity of Regia Aeronautica (Italian Royal Air Force) attacks as the stock of torpedoes at Sardinian airfields was nearly exhausted. The ships of convoy GM 1 sailed from the British Isles on 13 July 1941 as part of convoy WS (Winston Specials) 9C and arrived at Gibraltar on 20 July.^[4] Ships of the Mediterranean Fleet operating from Alexandria began making much radio traffic to divert attention from Gibraltar to preparations for a big operation in the eastern Mediterranean. Eight Allied submarines were deployed off Italian naval bases but Supermarina, the Italian naval headquarters, assumed the convoy was Ark Royal flying-off replacement aircraft to Malta and chose to remain in port. Leinster ran aground while leaving Gibraltar on 21 July and had to return to port. The Perla-class submarine Diaspro found the convoy on 22 July and launched torpedoes which narrowly missed Renown and HMAS Nestor.^[2]

The convoy came under low level attack by nine Savoia-Marchetti SM.79 torpedo bombers coordinated with five CANT Z.1007 medium bombers. Four Fulmars met the torpedo attack head-on and shot down a SM.79 before another SM.79 launched a torpedo which hit Manchester, before being shot down. Ark Royal launched seven more Fulmars which were unable to engage the high level bombers before they bombed, which failed to hit the merchant ships; three Fulmars were shot down. A later attack by two SM.79s sank Fearless killing 35 of her crew. Another bombing attack near-missed Firedrake causing damage requiring the destroyer to be towed back to Gibraltar. Bristol Beaufighters from Malta reinforced the Ark Royal Fulmars.^[2]

Cossack detected the torpedo-boats MAS-532 and MAS-533 approaching the convoy after dark but was unable to prevent them from torpedoing SS Sydney Star at around 03:00 on 24 July. The merchant ship, carrying 484 army officers and men in addition to its normal crew, came to a dead stop as it took on water. Fearing that the ship's pumps were unable to cope with the damage, the captain requested evacuation of the troops. The Nestor came alongside and took on board approximately 500 men via gangplank and Jacob's ladder, leaving the captain and a skeleton crew on the Sydney Star. The captain later estimated that his ship had taken on 7,000 long tons (7,100 t) of water. Nestor towed the damaged 11,000 GRT cargo ship to Malta, arriving at the Grand Harbour shortly after 08:00.^[2][5][6]

Seven empty ships sailed from Malta in Convoy MG 1 on 23 July to be convoyed back to Gibraltar by Force H.^[1] One was damaged by a torpedo bomber on the voyage west. Ark Royal lost six Fulmars defending Convoy MG 1 and the Malta-bound ships from Gibraltar and at least 12 Axis aircraft were destroyed by FAA fighters and the AA guns of the Royal Navy.^[7][a] The six merchant ships of Convoy GM 1 arrived in Malta on 24 July where they were observed by a CANT Z.506 reconnaissance seaplane, escorted by 42 Macchi C.200 fighters. Malta launched 22 Hawker Hurricane fighters, which shot down three of the escort without loss.^[2]

The Raid on Grand Harbour, an audacious attack by the elite Decima MAS, using explosive motor-boats (MTM) and manned torpedoes early on 26 July was thwarted by Radar and Ultra, ending in disaster for the Italians.^[2]

• Battle of the Mediterranean
• Malta Convoys

• O'Hara, Vincent P. (2009). Struggle for the Middle Sea: The Great Navies at War in the Mediterranean Theater, 1940–1945. London: Conway. ISBN 978-1-84486-102-6.
• Playfair, I. S. O.; et al. (2004) [1956]. Butler, J. R. M. (ed.). The Mediterranean and Middle East: The Germans Come to the Help of their Ally (1941). History of the Second World War, United Kingdom Military Series. Vol. II (facs. repr. Naval & Military Press, Uckfield ed.). HMSO. ISBN 978-1-84574-066-5.
• Rohwer, Jürgen; Hümmelchen, Gerhard (2005) [1972]. Chronology of the War at Sea, 1939–1945: The Naval History of World War Two (3rd rev. ed.). London: Chatham. ISBN 1-86176-257-7.
• Roskill, S. W. (1957) [1954]. Butler, J. R. M. (ed.). The War at Sea 1939–1945: The Defensive. History of the Second World War United Kingdom Military Series. Vol. I (4th impr. ed.). London: HMSO. OCLC 881709135. Archived from the original on 27 February 2022. Retrieved 24 November 2017.

• MV Leinster 1937