Aerial reconnaissance in World War II

A transformational growth in air reconnaissance occurred in the years 1939-45, especially in Britain and then in the United States. It was an expansion determined mostly by trial and error, represented mostly by new tactics, new procedures, and new technology, though rarely by specialized aircraft types. The mission type branched out into many sub-types, including new electronic forms of reconnaissance. In sharp contrast with the case during the pre-war years, by 1945 air reconnaissance was widely recognized as a vital, indispensable component of air power.

In the interwar years, reconnaissance languished as a mission type and tended to be overshadowed by routine aerial mapping. This was despite the growth (in the United States and Britain) of a doctrine of strategic bombardment as the decisive weapon of war. Experience would soon prove that bombing was completely ineffective unless accompanied by intensive aerial reconnaissance. In the 1930s, gradual technical progress in the leading air nations led to advances particularly in photogrammetry and cartography, but failed to be translated into a capable operational reconnaissance capability. The various parties went into the new war with mostly the same cameras and procedures they had used when exiting the last one. Stereoscopic imaging using overlapping exposures was refined and standardized for mapping. Color photography from the air was introduced in 1935 in the United States, but did not find widespread application. Experiments with flash bomb photography at night were carried out pre-war, but did not lead to an operational capability until later in the war. In the United States, apart from the case of small army-cooperation observation planes, the emphasis was almost completely on aerial mapping conducted by long-range bombers. In Germany, the Army Chief, Werner Freiherr von Fritsch, noted that in the next war, whoever had the best air reconnaissance would win – and thereby won himself a perfunctory mention in almost all subsequent works on the topic. Yet in all countries, initial doctrines were focused on battlefield observation, which assumed a relatively static front, as it had been in the previous war.

Strategic reconnaissance in its embryonic form began with the flights carried out over Germany by Australian businessman Sidney Cotton just before the outbreak of war in Europe. On behalf of first French and then British intelligence, Cotton outfitted civilian Lockheed Electras with hidden cameras and was able to snap useful footage during business trips. Cotton pioneered (for the British) the trimetrogon mount and the important innovation of heated cameras, fogging being the bane of high-altitude photography. However, a multi-lens trimetrogon had been used in the 1919 U.S. Bagley mapping camera, and Germany had heated optics during the Great War.

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