Properly speaking, Operation ‘Ironclad’ was the British seizure of Diégo Suarez on the north coast of the Vichy French island of Madagascar on 5 May 1942, and this was followed by the campaign that lasted to 6 November of the same year as a British-led land campaign, supported by a number of subsidiary amphibious landing, completed the seizure of this island.
As a result of ‘Magic’ decrypts, which in March 1942 revealed that Germany was pressing Japan to take and hold the island, the Allied leadership feared that the island’s ports might be used by Japan as, after its conquest of South-East Asia in the area to the east of Burma by the end of February 1942, the Japanese might contemplate further developments to the west. Such developments might include greater territorial ambitions, but would more probably take the form of the sea and air interdiction of the UK’s maritime lines of communications with the Middle East, India, Australia and New Zealand, which were vulnerable to attack by aircraft, surface ships and submarines in their routes across the Arabian Sea toward the Red Sea and the Suez Canal, and across the Indian Ocean and along the East African coast toward South Africa.
At this time Japanese submarines were able to operate freely throughout the Indian Ocean, and in March a Japanese aircraft carrier force conducted its ‘C’ raid into the Indian Ocean, an operation which drove Vice Admiral Sir James Somerville’s Eastern Fleet out of the north-eastern part of the Indian Ocean to a new base at Kilindini (the port of Mombasa) on the Kenyan coast of East Africa. The move laid the fleet open to a new angle of attack, so the possibility of Japanese naval forces using forward bases in Madagascar had to be addressed. Thus the use of these facilities by the Japanese not only threatened Allied merchant shipping, but also opened the potential for the destruction of an entire British fleet. Japanese submarines had the longest ranges of any such boats at the time, more than 10,000 miles (16000 km) in some cases. Should they operate from Madagascan bases, such boats could have threatened the Allied lines of communications in a region stretching from the Pacific and Australia, to the Middle East and South Atlantic.
Securing lines of communication
The Allied leadership accordingly decided to launch the ‘Ironclad’ amphibious assault on Madagascar with the northern port and naval base of Diégo Suarez as the primary objective. The expedition was mounted by forces from the UK under the escort of parts of Vice Admiral E. N. Syfret’s Gibraltar-based Force ‘H’, the rendezvous being made in South Africa where the whole force came under Syfret’s command, with Major General R. G. Sturges commanding the land forces, known as Force 121. The naval portion of ‘Ironclad’ consisted of the elderly battleships Ramillies and Malaya, fleet carriers Illustrious and Indomitable, heavy cruiser Devonshire, anti-aircraft cruiser Hermione, destroyers Active, Anthony, Duncan, Inconstant, Javelin, Laforey, Lightning, Lookout, Pakenham, Paladin and Panther and Australian Nizam and Norman, six corvettes and six minesweepers.
The all-British Force 121 comprised Brigadier V. C. Russell’s 13th Brigade and Brigadier G. W. B. Tarleton’s 17th Brigade (components of Major General H. P. M. Berney-Ficklin’s 5th Division, which had been earmarked for service in the Western Desert but which was now split up into brigades for detached service), Brigadier F. W. Festing’s 29th Independent Brigade Group, and Lieutenant Colonel W. S. S. Sanguinetti’s No. 5 (Royal Marine) Commando.
The Vichy French forces, under the command of Général Armand Léon Annet, the island’s governor, included about 8,000 troops, of whom about 6,000 were Madagascan and most of the other 2,000 Senegalese. Between 1,500 and 3,000 of these Vichy French troops were concentrated around Diégo Suarez. The Vichy French naval and air defences were relatively light and/or obsolete: eight coastal batteries, two armed merchant cruisers, two sloops, five submarines including Bévèziers, Héros and Monge, 17 Morane-Saulnier MS.406 fighters and 10 Potez 63 bombers.
The forces move on Madagascar
The ‘Y’ slow convoy departed Durban on 25 April with two special landing ships, six supply ships, one tanker and one hospital ship escorted by the cruiser Devonshire, three destroyers, the 3rd Escort Group, and the 14th Minesweeping Flotilla. The ‘Z’ fast convoy, carrying Force 151, followed three days later with five attack transports and three troop transports escorted by Syfret’s force (battleship Ramillies, carrier Illustrious, cruiser Hermione and six destroyers). On 3 May, the convoys and Rear Admiral D. W. Boyd’s reinforcement detached from Somerville’s Eastern Fleet, comprising the fleet carrier Indomitable and two destroyers, joined forces and Captain G. N. Oliver’s landing force headed for the area north-west of Madagascar with the cruiser Devonshire and Syfret’s covering force. On 3 May the convoys and the reinforcement detached from Admiral Sir James Somerville’s Eastern Fleet, under the command of Rear Admiral D. W. Boyd and comprising the fleet carrier Indomitable and two destroyers, joined the British invasion force. From there, Captain G. N. Oliver’s invasion fleet reached an area north-west of the island with the cruiser Devonshire, destroyers Active, Anthony, Duncan, Inconstant, Javelin, Laforey, Lightning, Lookout, Pakenham, Paladin and Panther, corvettes Auricula, Cyclamen, Freesia, Fritillary, Genista, Jasmine, Nigella and Thyme, minesweepers Cromarty, Cromer, Poole and Romney, and the transports. The covering force operated farther offshore with Ramillies, Illustrious and Indomitable, and Active, Duncan, Inconstant, Javelin, Lookout, Paladin and Panther. Hermione meanwhile undertook a diversionary sortie.
On 5 May carrierborne aircraft attacked the French airfields and ships. The Vichy French auxiliary cruiser Bougainville was sunk by aircraft from Illustrious, and the submarine Bévèziers was depth-charged and sunk: the boat was later raised. Following the completion of several reconnaissance sorties by South African Air Force aircraft operating from East Africa, the British landing in Courrier Bay, where the corvette Auricula struck a mine, took place as the troops were ferried ashore in landing craft in the face of no resistance. The further advance of the British troops was held up on 5 and 6 May by the Vichy French defenders. The landing of British commandos by the destroyer Anthony and the capture of important central installations led, however, to the rapid collapse of French resistance. The gunboat D’Entrecasteaux, which had provided gunfire support for the defence, had to be run aground after being hit by bombs from aircraft from Indomitable and the gunfire of the destroyer Laforey. On 7 May the Vichy French submarine Héros was sunk by the corvette Genista and aircraft from Illustrious while trying to attack the British main force. On 8 May the submarine Monge unsuccessfully attacked Indomitable before being sunk by the destroyers Active and Panther. The Vichy French submarine Glorieux and gunboat D’Iberville escaped to southern Madagascar and thence, later, to Toulon.
Seizure of Diégo Suarez
The primary object of ‘Ironclad’ was the naval base of Diégo Suarez, located at Antsier in Diégo Suarez Bay east of the town proper, but as access to this bay was controlled by French batteries it was thought tactically wise to land in Courrier Bay, west of the isthmus connecting Cap Amber with the mainland, before launching an overland advance of some 12 miles (19 km) to take Antsirane from the rear. The landing and the first stage of the advance progressed without undue difficulty, but the attack on Antsirane was then checked by strong Vichy French defences in the rear of Antsirane, defences that had not been revealed by the photo-reconnaissance flights. The initial deadlock was broken by the landing of a small party of Royal Marines in Antsirane in a courageous destroyer operation. This demoralised the defence, whose men then surrendered rapidly. The operation was over by the early morning of 7 May. A diversionary attack had also been staged in the east. Air cover was provided mainly by Fairey Albacore, Grumman Wildcat and Fairey Swordfish aircraft of the Fleet Air Arm, which attacked Vichy French shipping. A small number of South African aircraft aided this largely British effort.
Significant Vichy French forces withdrew from the area of Diégo Suarez toward the south, and now put up a stronger defence than had been anticipated. Reinforcements were received by each side. In the case of the Vichy French, the Japanese submarines I-10, I-16 and I-20 arrived on 29 May to be joined later by I-18, and a reconnaissance aeroplane from I-10 spotted Ramillies at anchor in Diégo Suarez harbour. However, the aeroplane was seen and Ramillies changed berth. I-16 and I-20 each launched a midget submarine (M-16b and M-20b), one of which managed to enter the harbour and fire two torpedoes while under depth charge attack from two corvettes. One torpedo severely damaged Ramillies, while the second sank an oil tanker. The two men of the crew beached their submarine and fled inland, where both were killed by Royal Marines three days later. Hostilities then continued at a low level for several months.
The 5th Division was transferred to India, and in June Brigadier W. A. Dimoline’s 22nd (East Africa) Brigade Group arrived, Brigadier G. T. Senescall’s South African 7th Motorised Brigade and Brigadier R. E. Hobday’s 27th (North Rhodesia) Brigade Group (including forces from East Africa) also landing in the following weeks. The British 29th Independent Brigade Group and the 22nd (East Africa) Brigade Group carried out the ‘Stream’ and ‘Tamper’ amphibious landings on 10 September at Majunga and Morondava, in the north-west of the island, to revitalise Allied offensive operations before the opening of the rainy season, and in September other landings were effected at strategic points round the island (‘Jane’ at Tamatave on 18 September, and Fort Dauphin and ‘Rose’ at Tuléar on 29 September).
Progress was slow, for in addition to occasional small-scale clashes with Vichy French forces, the Allied units also encountered scores of obstacles erected on the main roads by Vichy French soldiers. The Allies eventually captured the capital, Tananarive, on 23 September without much opposition, and also the town of Ambalavao on the road south through the centre of the island toward Ilhosy, where it separated to reach the ports of Tuléar in the south-west and Fort Dauphin in the south-east. The last major action was at Andriamanalina on 18 October, and Annet surrendered near Ilhosy, in the southern half of the island, on 5 November. The Allies had suffered about 500 casualties in the landing at Diégo Suarez, as well as 30 killed and 90 wounded in the operations which followed 10 September.