The italian general Giulio Douhet (1869-1930) since 1921 hee had theorized, in his work "The dominion of the air" , the possibility to put in knee the enemy with mass attacks of bombers on his back areas. The strong point of Douhet was: "To oppose resistance to earth and to try to decide the fates of the war in air".

In other terms its message was that no any civil population is able to withstand the bombing of cities and industrial centers too long , so victory is taken from who holds the supremacy of the air. Theories that didn't have immediate succession, but subsequently they were at the base of the principles of allied strategic bombardment in Asia and in Europe.

With the birth of the Third Reich, in the years of the German rearmament, a choice was operated: to create a specialized air force in the support to the ground forces and hinged on light and medium bombers that were able to get rapid successes with quick and decisive strikes, increasing enormously the penetration ability of the ground forces, therefore this was more a tactical that strategic air force.

In the United States and in Great Britain, in that same years, following Douhet, they aimed their efforts above all on the creation of heavy strategic bombers. They planned a war of slow and bloody dismantlement of the morale of the enemy that the Countries of the axis would have experimented, particularly, from 1943 .

In 1935 the British physicist Watson-watt published a study about the discovery and location of an airplane through radio apparatuses , from this study, immediately past to the experimental phase he arrived to that Radio detection and ranging system, commonly called radar. He can not know then what service he was making to his own Country: when in fact in 1940 G.B. fought the Battle of Britain on the southern coasts of the Great Britain an imposing chain of installations of radiolocalizzation (the Chain home) wich was already ,after only five years of experimentation, constituting a fundamental element of advantage for the RAF.

In 1938 the German general von Reichenau wrote: " have been more useful two years of war experience than a decade of training", referring to the experience of the war of Spain. In fact, beyond of the famous terrorist bombardment of the Legion Condor on Guernica (wich inspired Pablo Picasso's masterpiece "Guernica") they, formed in the Luftwaffe the professionalities of a lot of fighter pilots and bomber crews between em Werner Moelders and Adolf Galland ; also was developed a new tactic of wing fighting , based on the division of the wing in couples formed by a leader, that was dealt only to attach, and from a wingman that had the assignment to cover him the six.

Many Russian pilots also matured experience in this war but anybody of em was going to influence the fates of the Second world war, beheaded like they were all the vertexes of the Soviet aviation during the stalinian purgations . Only advantage drawn from the Soviets from Spanish experience was the planning of the Ilyusin IL2 Sturmovic, a greatly armored and armed Tactical Support attack plane that became the nightmare of the Wermacht from 1942 .

Italians also participated in this war and the Regia Aereonautica, exalted from the mussolinian regime , fought with success in the Spanish skies; at least one thing was learnt by Italian pilots , that had fought there with the Fiat CR42 (and with the even more obsolescent CR32) they understood that the era of the biplanes was ended: by now replaced from the fastest monoplanes with heavy wing load and retractable gear like the German Messerschmitt bf 109 and the Soviet Ilyushin I-16.

what are the planes in the photos (to see em go in the italian version;) :To left a Me bf109 Emil (preserved, police squad, to Duxford, GB); to the right the Ilyushin I-16 (in the Museum of the big patriotic war in Moscow); under C42 rolling

A year before the burst of the war Germany effected a measure to a little worrisome the interdiction of the proper air space to foreign airplanes with the exception of determined corridors. reaction of the British secret services didn't delay. It was envoy in missions of photographic recognition, taking worthy risks of his celluloid successor 007, the industrialist Australian Sidney Cotton, famous in all Europe for his dowries of acrobatic pilot. Owner of the Dufay Color, then industry was not him to the vanguard in the development of films to colors difficult to bring around secretly for Germany, on its civil airplane, material photographic. Its reportages would have furnished informations on the fortified line Sigfrid that on the location of the German industrial installations.