A transformational growth in aerial 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.
Pre-war situation 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.Babington Smith, p78; Stanley, p268 et passim Color photography from the air was introduced in 1935 in the United States, but did not find widespread application.Goddard, 240 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.Goddard, 127–131 e.a. 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.Babington Smith, p6 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.Kreis, 81, e.a.
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.Leaf, pp14–38 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.Goddard, p25
Early Western reconnaissance Sidney Cotton's work found only grudging approval with the Royal Air Force, but eventually his work was incorporated into No. 1 Photographic Development Unit (PDU) at RAF Heston and then RAF Benson, a unit from which most later British air reconnaissance developed. (It soon was renamed 1 PRU, R for reconnaissance.)Leaf, p18 Key to the RAF's intellectual ascendancy in reconnaissance was the establishment of the Central Interpretation Unit (CIU) at RAF Medmenham. Priority tasks of this unit were to prepare target folders and to chart Axis air defenses. In short order, it began to evaluate the effectiveness of bombing.Ehlers See Photo interpretation.
At first Britain used a handful of hastily modified Spitfires (PR 1) and some medium twins (Bristol Blenheims) for photographic reconnaissance, supplemented by in-action footage shot from regular bombing aircraft. At this time the RAF still used the vintage F8 and F24 cameras, later adding the larger F52. The F24 became especially useful in night photography.Stanley, Staerck Thanks to bomb damage assessment (BDA) the complete failure of precision daylight bombing soon became apparent, the vast majority of bombers not even coming close to their targets. This resulted in heavier demands on reconnaissance for before-and-after photography; and the documented poor results (as well as heavy losses) led to a shift to night-time area bombing.
Britain was far behind Germany in optics, and at one time 1 PRU took two Zeiss Ikon cameras with 60 cm lenses from a lost Ju 88 and used them for high-altitude photography.Leaf, p48
By 1941, the RAF had a capable reconnaissance arm (1 PRU) centered at RAF Benson, supported by a nascent infrastructure in interpretation and analysis. The Combined/Joint Intelligence Committee (CIC) ensured centralized tasking for critical objectives. The RAF led this field by far, and in 1941 several American observers from both the U.S. Army Air Corps (USAAC) and the U.S. Navy were sent to England to investigate RAF reconnaissance methods.Goddard. See also Arnold, Henry: Global Mission. General Arnold was one of the fact-finders in Britain in spring 1941.
Unlike the case in the previous war, French reconnaissance was now comparatively ineffective on all levels, and entirely lacked a strategic perspective. Most aircraft allocated to the mission type were obsolete. Large numbers of open-cockpit Mureaux 115/117 and light twin Potez 630 series were assigned to Army cooperation according to observation doctrines from the previous war. However, the new and scarce Bloch 174 twin distinguished itself by its high performance. Noted writer and reconnaissance pilot Antoine de Saint-Exupéry flew this aircraft before the fall of France.St. Exupery: Flight to Arras, 1942.
Italian reconnaissance over Ethiopia
The Istituto Geografico Militare acquired aerial photographs to sustain its war effort against Ethiopia in the mid 1930s. The aerial photographs over Ethiopia in 1935-1941 consist of 8281 assemblages on hardboard tiles, each holding a label, one nadir-pointing photograph flanked by two low-oblique photographs and one high-oblique photograph. The four photos were exposed simultaneously and were taken across the flight line. A high-oblique photograph is presented alternatively at left and at right. There is approx. 60% overlap between subsequent sets of APs. One of Ermenegildo Santoni's glass plate multi-cameras was used, with focal length of 178 mm and with a flight height of 4000–4500 metres above sea level, which resulted in an approximate scale of 1:11,500 for the central photograph and 1:16,000 to 1:18,000 for the low-oblique photos. The surveyors oriented themselves with maps of Ethiopia at 1:400,000 scale, compiled in 1934. The flights present a dense coverage of Northern Ethiopia, where they were acquired in the context of the Second Italo-Ethiopian War. Several flights preceded the later advance of the Italian army southwards to the capital Addis Ababa. As of 1936, the aerial photographs were used to prepare topographic maps at 1:100,000 and 1:50,000 scales.IGM, L’Istituto Geografico Militare in Africa Orientale, 1885 - 1937, Istituto Geografico Militare, Roma, 1939
German reconnaissance capabilities
Despite a considerable technological and numerical head start, Germany gradually neglected aerial reconnaissance, at least relative to Britain. The reason, grounded in history and geography, was that Germany had no strategic bombing doctrine and viewed air power as an auxiliary of land armies. Numerous Aufklärungs (up-clearing, i.e. reconnaissance) units were established for marine and ground support purposes, but while this was effective in the tactical sense, the intellectual investment in interpretation, analysis, and strategic estimation lagged. From the German perspective, this was defensible considering that about 90% of the action lay in large land-battles in the East, and an expensive long-range air capability would have been unlikely to effectively change the outcome.Hooton
Leading up to the war, the United States developed an indigenous high-quality optics capability led by Bausch & Lomb of Rochester, N.Y.; however this company had been allied to Germany's Zeiss-Jena. Nonetheless, the American reconnaissance expert, Captain George Goddard, said that he much coveted German technical leadership, specifically as represented by Carl Zeiss Jena optical works, and he was pleased to briefly occupy that facility at the end of the war. The Luftwaffe (German Air Force), expecting a quick victory, did not build an integrated reconnaissance and interpretation capability like the Anglo Allies did.Goddard, pp340-41
Before 22 June 1941, German reconnaissance was far predominant in frequency with many daily sorties throughout the region. Leading up to the invasion of France, concentration was on ports, forts, railways and airports, using mostly Dornier Do 17Ps and Heinkel He 111Hs, already vulnerable types, and rapid conversion to Junkers Ju 88D, later Ju 88H followed. Losses were on the order of 5–10 per cent. A regular daily weather reconnaissance was kept up over the North Sea. Maritime reconnaissance from France and Norway reached well west of Ireland to the coast of Greenland using Focke-Wulf Fw 200 Condor and various multi-engine seaplanes.Hooton, pp197–201 Germany used the LZ 130 Graf Zeppelin airship for signals intelligence sorties targeting RAF radar stations in 1939.
German units were divided into Fernaufklärer (long-distance), Nahaufklärer (tactical, subordinate to Army command), Nachtaufklärer (night photography) and maritime and special units. Command structure and unit designations changed incessantly. Each staffel (squadron, roughly) had a Bildgruppe of interpreters, who would telephone urgent intelligence to nearby headquarters. Film and analyses would go to Fliegerkorps (higher-level) staff later; eventually top-level staff at the Oberkommando der Wehrmacht (OKW) headquarters at Zossen near Berlin would receive the products for filing and possibly strategic integration.Hooton, p199; Babington Smith
Germany emphasized tactical reconnaissance and invested considerably in modified aircraft – primarily Ju 88s and Junkers Ju 188s – and in types such as the asymmetric Blohm & Voss BV 141 (20 built) and the twin-boom Focke-Wul Fw 189 Uhu (nearly 900 produced). This Nahaufklärung was primarily successful on the Eastern Front where immediate results were desired, and these units were directly under Army field command. For special demanding tasks a high-altitude photographic reconnaissance aircraft, the pressurized Junkers Ju 86P was available in very small numbers, but it could not survive after 1943. Also pressurized, the Junkers Ju 388L could reach and much higher airspeeds than the Ju 86P but only 50 examples were built late in the war and few saw operational service. Fighters, often with dual oblique cameras in the rear fuselage, were pressed into service for reconnaissance where their speed was necessary and performed well in this role. German reconnaissance against well-defended England was relatively ineffective.Stanley
Prior to Operation Barbarossa, the German attack on the USSR, the Luftwaffe carried out extensive aerial observation of European Russia. This was possible partly because Soviet air opposition was weak, and because of the Soviet leadership's conviction that Germany would not attack. The Luftwaffe maintained air superiority in the East until late in the war, but simply could not bring enough resources to bear for air power to be decisive. Italy and Japan, performed long-distance reconnaissance prior to meeting stiffening opposition in 1942. Japanese aircraft reconnoitered the Philippines prior to 7 December 1941.
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