This was a British unrealised plan to take the Cape Verde islands group, a possession of neutral Portugal off the west coast of Africa, and one of the many schemes that appealed to Winston Churchill as First Lord of the Admiralty and then, from 10 May 1940, prime minister of the UK (1940/41).
Although he did not have any definitive information, Churchill rightly intuited that the Germans, in particular the navy, would like to take the Azores and Canary island groups.
Grossadmiral Erich Raeder, the commander-in-chief of the German navy, met with Adolf Hitler on 26 September 1940, just before the 'Seelöwe' invasion of England was indefinitely postponed, to emphasise that an operation against the Azores island group was still a naval necessary, but at the same time he emphasised that the navy should first be given resources adequate for the undertaking. Raeder added that the enlargement of the navy was long overdue to build up the fleet, and that a powerful navy would make feasible the seizure not only of the Azores islands but also the Cape Verde islands, which possessed a similar strategic importance against the British maritime lines of communication: in German hands the Cape Verde islands would be an excellent base for attacks on north/south convoys sailing to or from England to southern Africa and India, just as the Azores island would serve the same role against east/west convoys to and from the Americas.
Once it had the two island groups, Germany could dominate maritime traffic in the central part of the Atlantic and, according to Raeder, convince the USA to end the sacrifice of her merchant marine on suicidal convoys in support of the UK. German possession of the island groups, Raeder added, would convince the USA to remain neutral and possibly even to abandon the UK.
But should the USA enter the war, it was even more important for Germany to possess a powerful fleet and the Atlantic bases from which to meet the new threat. Without an adequate fleet, Germany could do nothing if the USA attempted to extend the war into the Atlantic, as she has been threatening, and to occupy any or all of the Canary, Cape Verde and Azores islands, and even Greenland, and possibly also move into French West Africa to seize Dakar.
Hitler agreed that the islands might easily be taken by the Luftwaffe with its airborne troops, but added that the islands could then be held only by troops and matériel transported by a navy strong enough to challenge the British and US fleets.
Raeder was adamant that the German navy had to be enlarged, for if the UK’s maritime lines of communication were severed it would be only a matter of time before she had to capitulate. However, it was clear that the navy was not being enlarged as quickly as had been ordained in the 'Z-Plan', shipyards were not getting the strategic materials they needed, and Hitler had given the Atlantic islands a low priority.
An operation against the Azores islands demanded at least tacit approval from Spain, which was a fellow Fascist power and supposedly sympathetic to the Axis cause. In combination with the fact that Germany seemed currently to be winning the war, it seemed possible that General Francisco Franco y Bahamonde, the Spanish leader, might give his approval to an operation against Portuguese territory, especially one that would hasten an Axis victory. A surprise air- and submarine-borne attack on the Azores would be followed by the landing of large numbers of troops and matériel delivered by the navy. Such a move should be made as soon as possible, and certainly before the USA entered the war, an eventuality which the German high command was sure would occur sooner rather than later.
Germany’s plans now included 'Felix', which called for an air attack on Gibraltar by warplanes based in south-western France beginning on 10 January 1941 and co-ordinated with an artillery bombardment from German heavy guns secretly emplaced in nearby Spanish bases. This, the Germans believed, would also have the effect of destroying many of the ships of Vice Admiral Sir James Somerville’s Gibraltar-based Force 'H' and prevent the arrival of British naval reinforcements. About three weeks later German ground forces would arrive to spearhead a ground attack: two divisions coming through Spain, one armoured and one motorised, would cross the Strait of Gibraltar into French Morocco to seize control of the Atlantic seaboard. Three more divisions would head to the Portuguese border where they would be in a position to invade the country and drive back any British attempt to make a landing. German forces would then occupy Gibraltar and effectively close the Mediterranean to the British from the west.
By 4 November 1940, however, the Oberkommando der Wehrmacht was becoming cooler to 'Felix', largely as a result of the indecisive results of the meeting between Hitler and Franco at Hendaye on the Franco-Spanish order during 23 October. Hitler reiterated that he had not forgotten the advantage of possessing the Atlantic island groups, and remained confident that if pressure was applied to Franco, the Spanish leader would bring his country into the war on the side of the Axis and provide free passage for German ground troops across Spain for an assault on Gibraltar.
Three German motorised divisions were now prepared and waiting on the French side of the Pyrenees mountains for permission to cross into Spain. The OKW had lost belief in the feasibility of 'Felix', though, and now raised three major caveats: firstly, was Franco really ready to take his country to war; secondly, even as a passive ally would Spain allow German troops to cross her territory; and thirdly, what were Franco’s real intentions about Gibraltar? This last was notably important, for the OKW was concerned that Franco wanted Gibraltar for Spain and not as a German base at the western ed of the Mediterranean.
Hitler’s response was that if 'Felix' was now impractical, was the seizure of the Cape Verde islands an alternative. A Portuguese colony some 385 miles (620 km) to the west of Dakar off the coast of French West Africa, these would provide an excellent base for U-boat operations in that part of the South Atlantic which saw huge amounts of British maritime traffic between the UK and her African possessions, India, Far East and Australasia.
By this time, however, the Oberkommando der Marine had become altogether more cautious about such a move as it would depend on Vichy French co-operation in nearby West Africa, but this would be problematical as Dakar was apparently a hotbed of Free French sentiment. Moreover, the undertaking would a large commitment by a navy which still lacked the resources to provide it. In these circumstances, the OKM argued, it would made greater sense to abandon any short-term idea of seizing the Cape Verde islands and, with this, the possibility of bringing Portugal into the war on the side of the British, who would then take the opportunity to occupy the Portuguese colonies of Madeira, the Cape Verde islands and the Azores islands.