'Bugle' (i) was a British unrealised early plan for the occupation of the Canary islands group, a strategically important Spanish possession in the Atlantic Ocean (June 1940).
Scientists of the Ahnenerbe, the Nazi scientific institute established in 1935 by SS-Reichsführer Heinrich Himmler and funded by the SS to undertake research into the supposed archaeological and cultural history of the Nazi-hypothesised Aryan race, planned to work in the Canary islands group, but were forced to postpone the project when World War II broke out in September 1939. Istread the Ahnenerbe funded Spanish excavations, provided photographic equipment, and lent aircraft to conduct aerial surveys of archaeological sites. General Francisco Franco y Bahamonde, the Spanish dictator, at first declared Spain a non-belligerent. Adolf Hitler conceived of seizing the Azores and Canary islands groups early in the war, as air and naval bases, but was dissuaded from this adventure by his naval staff, who appreciated that while Germany might be able to seize the islands, it lacked the naval strength that would then be needed to supply the island and hold them.
In 1940 Spain began constructing large military complex at Las Palmas. President Franklin D. Roosevelt saw the Canary islands group as a potential 'German springboard' for 'aggression upon the Western Hemisphere'.
Unlike the Portuguese-controlled Azores islands group, the Canary islands group played no major role in the War. The British were concerned at first because it was not clear whether or not Franco would bring Spain intro the war on the side of the Axis. In Axis hands, the islands could have paved the way for a major dislocation of the vital sea commerce between the UK and its empire, which provided crucial manpower and materials to the UK. Even if the Germans did not seize the Canary islands group, Spanish permission allowing Germany to use the islands for the refuelling and resupply of U-boats would turn the islands to become an important support for U-boat operations. As a U-boat base, however, the Canary islands group suffered a serious limitation as fuel and equipment would have to be brought in by surface ships, and such traffic would be very vulnerable to British naval interdiction.
The British considered 'Bugle' (i) in 1940, and proceeded further with 'Puma' in June 1941. These were but two of many British contingency plans to deal with the possibility of German plans to move against Spain and Portugal.
Spain denied the German navy the use of the Canary islands group for the refuelling and rearming of U-boats in July 1941, but the British remained prepared to seize the Canary islands group in the event that the Spanish attacked Gibraltar. Denying U-boats access to the Canary islands group, however, went a considerable way toward ending the British concern with the Canary islands group and, after Franco decided to change Spain’s status from non-belligerent to neutral, the Allies decided to treat Spain as such in 1942.