The British invasion of Madagascar, 1942: an unsung success that advanced amphibious warfare

The British invasion of Madagascar in 1942 gets little attention. This is partly because it took place in the Indian Ocean, an important theatre that is too often overlooked, but also because it was limited in scale and duration compared to other wartime campaigns. Yet it presents interesting aspects in terms of broad national strategy; the design and conduct of military operations; and the development of Britain’s amphibious capability.

Why? National Strategy

The first question is why the operation was conducted in 1942, a time when British forces were badly overstretched. The invasion was contemplated because of the strategic location of Madagascar (see Map 1): established enemy bases there could choke off vital shipping routes to East Africa, the Gulf, the Middle East, India and the Far East, particularly with the Mediterranean route effectively closed.

But while the impact of Germany or Italy seizing bases there – especially the port of Diego Suarez, referred to as ‘the Scapa Flow of the Indian Ocean’ (comparing it to Britain’s main wartime naval base in the Orkney Islands) – would have been enormous, the likelihood of their being able to do so was distinctly low.

Despite the occasional hint from (often questionable) sources that some Axis plan was afoot, core British interests could be achieved simply by routine Royal Navy patrols denying the enemy use of the island. Churchill might have yearned for the more ambitious aim of controlling it, as he did to disastrous effect with the other key Vichy colony at Dakar, where a 1940 attempt to seize the port failed badly, but the forces that would have been required – and even more, the shipping to transport them – were more urgently needed elsewhere.

The picture changed, however, as Japan became increasingly threatening. The benefits for it of taking bases in Madagascar were even clearer and its ability to deploy and sustain forces there was far greater than was the case with Germany or Italy. Further, the British government became concerned at the possibility that, rather than Japan needing to conduct an invasion to seize Diego Suarez, Vichy France could invite them in, as they had in Indochina (thereby dooming Malaya and Singapore).

Yet this still did not lead to Britain prioritising Madagascar over other commitments. Rising concern about Japan had even greater implications for India and Ceylon (modern-day Sri Lanka); the threat to Madagascar raised it as a concern but did not lift it to the top of the list. The attack on Pearl Harbor in December 1941 reinforced the impression that Japan ‘could take bold action when they had decided to’ but reinforcing India remained the priority. It was only in March 1942, with further Japanese thrusts into the Indian Ocean, that the War Cabinet decided to launch an expedition against Madagascar – and even then, it was opposed by Alan Brooke (Chief of the Imperial General Staff and Churchill’s most influential military advisor). The rationale was to deny Japan a base from which its forces could cut off essential sea communications, while also providing an additional naval base should the British Eastern Fleet be forced to retreat from Ceylon. The War Cabinet decided that this prize was worth the risk involved in a short delay to reinforcing India.

How? The conduct of the campaign

The key conclusion is that Operation ‘Ironclad’, the initial stage of the British invasion, was conducted effectively, suggesting that the experience of previous failures in Norway and Dakar had been properly digested.

The commanders devised a plan that sought to achieve – and, crucially, exploit – surprise to collapse French resistance quickly. This would achieve the two key aims of minimising French (and British) casualties and of securing a rapid success that would allow the forces involved to move on elsewhere. The lead units were trained in amphibious operations and benefitted from a rehearsal in February 1942 around the River Clyde in Scotland. A strong supporting naval force accompanied them, though constrained resources led to support elements for the land force being ‘cut to the bone’.

The initial objective was confined to Diego Suarez; ideally, the operation would have taken the rest of the island, but this was deemed ‘nice to have’ rather than ‘must have’.

The initial landing on 5 May 1942 achieved surprise as intended (see Map 2). When mounting friction and French resistance threated to grind the advance to a halt, a bold combination of a further, improvised landing behind the main enemy position combined with a night-time assault brought the town under British control by the third day.

With the French governor playing for time, and the immediate threat to India becoming less pressing, Britain planned the second phase of the campaign to begin in September. Operation ‘Stream-Line Jane’ saw further amphibious landings against Madagascar’s two remaining French-held ports on the west and east coast, followed by an advance overland against the capital. These landings again exploited the mobility of naval forces to achieve surprise, with the support of several diversionary operations and effective security. The campaign was a clear success: the governor finally surrendered in November, giving Britain control of the island.

So what? Implications

The campaign was particularly significant for the advances that it demonstrated in amphibious warfare. This was not as neglected in the interwar period as is sometimes suggested, but the work done was more setting the conceptual and organisational foundations than procuring the ships and craft required to turn this potential into reality.

Madagascar saw the first use of aircraft operating from carriers, and of tanks, to support an amphibious operation. It saw the first use of a Tank Landing Ship – an improvised vessel which, though flawed, was enough to prove the concept of what later became ‘a war-winner’. It confirmed the value of work that was underway to provide purpose-built headquarters ships for the command and control of amphibious operations, and for specialised units to manage the flow of supplies onto and off the beaches. Most of all, it tested and proved emerging concepts and doctrine for amphibious warfare. The British and their allies would apply and further develop these lessons in campaigns in the Mediterranean and then, to great strategic effect, in the Normandy landings in 1944.

The invasion of Madagascar revealed some shortcomings, but the campaign showed that Britain was making strong progress in ascending the difficult learning curve of amphibious warfare. It receives far less attention than failures such as Norway or Dieppe but really deserves to be more widely known.

For a more detailed exploration of the 1942 British invasion of the Vichy-held French colony of Madagascar, read Dr Tim Benbow’s open access article in the International Journal of Military History and Historiography.