Intelligence was a matter of substantial importance in World War II. It was of greater importance than of virtually any other major war in history. The primary reason for this was that vast amounts of intelligence were available to any country which was willing to string up radio antenna and invest in training staff to receive and decide messages. World War II was the first war in which electronic (radio/wireless) messages were a major factor. The telegram became important in the 19th century, but telegram messages sent over wire lines were difficult to intercept. They were not impossible (as the British showed with the World War I Zimmerman telegram). And mobile mechanized warfare as initiated first by the Germans and subsequently by the Allies required vast numbers of easily intercepted (but less easilly decoded) messages. The issue of code breaking is one of the most important aspects of World War II intelligence. Here the British and Americans excelled and reaped very substantial benefits. The Germans were particularly vulnerable because they had such confidence in their Enigma machine. Very little is known about Soviet code breaking. The Germans had some successes, but generally failed at breaking Allied codes. Neither did the Japanese manage to break Allied codes. Electronic inteligence was not the only methods. The Soviets operated the most sucessful spy networks, in both Allied and Axis countries. The existence of Communist Party organizations proved a great asset. The major German spy was believed to have been before the War in encouraging Stalin's purge of the Red Army, but that has been discounted by many historians. German intelligence during the War was nothing short of a disaster. The Soviets manage to surprise the Germans with a series of offensives beginning with winter counter offensive before Moscow (December 1941). Of course the German intelligence operation was the fact that the head of the Abwehr, Admiral Canaris, was actively working against the NAZIs. The greatest Allied achievement may have been in fooling the Germans about the location of the D-Day landings. Allied opperatives also provided valuavle information about the German rocket program. The major surprise German operation of the War was the Ardennes offensive which Allied intelligence failed to detect, in part because of German signals duscipline (December 1944).
Military intelligence is surely as old as warfare itself. The objective of military intelligence is to assess opportunities and risks associated with friendly and enemy operations. It is also used to reduce reduce uncertainty associatted with terrain and weather conditions. The basic tasks are to: 1) acquire informtion, 2) analize that data, and 3) securely deliver actionable information to the appropriate commanders. Traditionally the principal sources of information have been human sources. This includes interviewing captured enenmy combatants and civilians. There are also academic sources, such as published texts with maps offering terraine information or in naval warfare, iceanographic charts. Until the 20th century, the calvalry was an important source of information on both terraine and enenmy movements. Modern weapons greatly reduced the role of calvalry in Wotld War I and it played a minor role in Workd War II in the area of intelligence. Another source of information is spying, but this is often carried out by organizations other than the military itself, although this varied from country to country. Intelligence outside the military structure was often at first not trusted by the military, but this chnged over time when Allied Ultra proved to be so accurate. Technological advanced created two new areas of intelligence acquisition: 1) photo reconisance and 2) signals intelligence. Both first appeared in World War I, but were perfected during World War II, especially signals intelligence.
Photo reconisance was first used in World War I. The new air planes provided a new panorama of the battlefield never before available to commnders. It was the first military use of air planes. The limited range of planes, however, limited the view to the front lines and immediate rear areas. And the absence of radio affected the timlines of the reports received. This changed in World War II with the greater range of aircraft and the widespred availbility of radio. Huge numbers of photographs were taken by the combtant countries. Photo reconisance was used by all World War II combatants. The Germans extensively used photo reconisance on the Eastern Front, including the preparation for Barbarossa. Stalin ordered the Red Air Force not t engage Luftwaffe reconisance air craft so Hitlercould see that there were no threaenig formations. The greatest use was made by the Allies because of the command of the air achieved once the United States entered the War. The strategic bombing campaign required detailed photo reconisance to plan and evaluate missions. Also the various amphibious operations in Europe and the Pacific required extensive photo reconisance, especially D-Day. Photo reconisance was an important part of the campign against the V-weapons.
The major beligerant powers of World War II developed various encrytion systems. Those systems and the cracking of them played important roles in the War. Wireless radio communication was critical for directing military forces often spread at great distances and moving rapidly, spread all over the world. But radio messages were not secure and could be intercepted. Thus important messages had to be sent in code. All the major powers developed complex machines that could rapidly convert typed text into code and then on the other end back into code. Early histories of the War were written without benefit of information on these systems and code breaking efforts. The Germans thought that they had solved the problem and that theie Enigma Machine could not be cracked. They proved to be wrong. The British cracked it the Ultra program provided timely information on Wehrmacht activities. The most secure system proved to be the American SIGABA system. Information on the code systems for the most part has now been declassified and the details are available to historians. There were major impacts on the North Africa campaign, the Battle of the Atlantic, and the early stages of the Pacific War. The only aspect of Woeld War II codes that is not available to historians are Soviet efforts at code breaking. The Soviets and now the Russians have been reluctant to open their archives to historians.
Intelligence was a matter of substantial importance in World War II. It was of greater importance than in virtually any other major war in history. The primary reason for this was that huge advances were made in radio (wireless) communications. And the vast expanse of World War II battelfields as the nature of modern mobile warfare required that radio be used. Bltzkrieg required radio communications. Thus huge amounts of electronic communications were broadcast. And nothing could be any more insecure. It meant that vast amounts if military communications was up for grabs. It was readily available to any country which was willing to string up radio antenna and invest in training staff to receive and analize the messages. Many mesages were sent in the clear. The most important were encoded. World War II was the first war in which electronic (radio/wireless) messages were a major factor. The telegram became important in the 19th century, but telegram messages sent over wire lines were much more difficult to intercept. They were not impossible (as the British showed with the Zimmerman telegram), but they were difficult to intercept. And mobile warfare as initiated first by the Germans and subsequently the Allies required vast numbers of easily intercepted (but less easilly decoded) messages. These messages needed to be encoded through a system that could be easily decoded by the country involved, but would defy code breaking by the enemy. A complicated decodeong system was impossible given the number of messages. Naval warfare also required large numbers of radio messages. Both the Germans and Japanese learned after World War I that their codes had been cracked by the Allies. And the Soviets learned that their codes had been cracked. As a result, these countries adopted much more elborate code systems. The Germans and Japanese developed cypher machines. The Soviets developed a single pad system. The Germans and Japanese proved particularly vulnerable because they had such confidence in their cypher machines. And they sent a huge volume of messages which significantly increased the vulnerability of the machines. The Germans also attemptd to read Allied signals. And they had some successes, mostly with British communications. They generally failed at breaking Allied codes. Neither did the Japanese manage to break Allied codes. Very little is known about Soviet code breaking efforts.
The Allied war effort was enormously assisted by code breakers. Both German and Japanese codes were broken, providing vital information to Allied military planners. A Polish mathematician played a key in cracking the German military's suposedly unbreakable cipher machine--enigma. The Poles in cooperation with the French were able to construct an enigma machine whicg they turned over to the British just before the German invasion. Additional work done at Bletchly Park allowed the British by late 1940 to read large numbers of Luftwaffe messages. The Kriegsmarina code was also broken, but was more difficult because their operators were more careful to follow pricedures. Many messagesre read because operators did not follow procedures. The Kreigsmarine also added a fourth rotor. Enigma traffic played a vital role in the Allied victory against the U-boats and in the cutting off of Rommel's supplies in North Africa. American breaking of the Japanease naval code was a key element in the naval victory at Midway. It also allowed American pilots to shoot down Adnmiral Yamamoto--the architect of the attack on Pearl Harbor. The Germans also had some successes. The Germans were able to read British naval messages in early 1940 which allowed them to counter planned Anglo-French operations in Norway with their successful invasion of Denmark and Norway.
Electronic inteligence was not the only method of intelligence gathering. The Soviets operated the most sucessful spy networks, in both Allied and Axis countries. The existence of Communist Party organizations proved a great asset. The Red Army although not highly respected by the Wehrmcht, proved very adept as desguising their major offensives. The major German spy achievement may have been before the War in encouraging Stalin's purge of the Red Amy. German intelligence during the War was nothing short of a disaster. The Soviets manage to surprise the Germans with a series of offensives beginning with offensive before Moscow. Information on almost all of the German offensives leaked out, although neither the Soviets or the Allies took advantage of this. Of course the German intelligence operation was the fact that the head of the Abwehr, Admiral Canaris, was actively working against the NAZIS. The greatest Allied achievement may have been in misleading the the Germans about the location of the D-Day landings. Allied opperatives also provided valuavle information about the German rocket program. The major surprise German operation of the War was the Ardennes offensicve which Allied intelligence failed to detect, in part because of German signals discipline (December 1944). The Japanese collected information on Pearl Harbor before the War, but have few intellgence successes during the War. They did obtain information on Singapore defenses. And the Ichi-Go offensive in China was based on information they acquired about the planned strategic bombing campaign. The results, however, were negated when the Americans seized the Mariana Islands in the Central Pacific.
Brown, Anthony Cave. Bodyguard of Lies (Harper & Row). This is a source recommended by a reader that we have not yet had the opportunity to address.
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