Figure 1.--

The Allied war effort was enormous assisted by code breakers. Both German and Japanese codes were broken, providing vital inforamtion 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 Britih 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.

Importance

The Allied war effort was enormous assisted by code breakers. Both German and Japanese codes were broken, providing vital information to Allied military planners.Codebreaking was more important in World War II than any other war in history. This was because advances in radio meant that for the first time large numbers of messages were sent by radio and this meant that they could be intercepted and used by the enemy. Radio existed in World war I, but was too bulky to be effectively used by land forces. It was more a factor in naval war, but interception was primarily used by enemies for directional location. This had all changed by the time of World War II. The Germans and Japanese were the most exposed. The Germans developed the doctrine of Blitzkrieg War which placed an emphasis on command and control. This mean that German plnes and tanks were equipped with radio. French tanks on the other hand did not have radios and neither did many French infntry units. The results showed when the Germans attacked (May 1940). But transmitting so many messages meant that the Germans were vulberable to electronic intelligence. To prevent this they built the Enigma Machine which they believed was impossible to crack. Cracking Enigma and the Uktra project is one of the great stories of World war II and provides the Allies important advantages as critical times. Ultra intelligence was especially important in the critical Battle of the Atlantic. Naval war involved extensive use of radio and this was especially important over the vast expanse of the Pacific War. American and British cracking of Japanese codes played a major part in the critical early phase of the Pacific War when the Japanese had a military advantage. The American victory at the decisive Battle of Midway was made possible by cracking the mprial Navy's codes.

Country Code Systems

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. Early histories of the War were written without benefit of information on these systems and code breaking efforts. The ibformation 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.

American codes

British Codes

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.

German codes

A major problem in World War I was that once an offence was set in motion, the high command lost contact and the ability to direct forward elements. Advances in radio meant that World war II commanders could keep in contact contact with forward units no matter how rapidly they were moving. But this raised a serious problem in that radio broadcasts could be intercepted by the ememy. The German sollution to this problem was the Enigma Machine. This was an advanced electro-mechanical cipher machine. It was used by all branches of the German military including the Wehrmacht, Luftwaffee and Kriegsmarine. The different services developed different machines and varied in their operational procedures. The Enigma machines were the principal German device for secure wireless military communications throughout the War. The German military was concerned about security and thus developed increasingly complex types which made it more difficult for code breakers to crack. The most complex Enigma machine type was developed by the Krigsmarine for U-boat operations, in part because of rising U-boat losses. The Kreigsmarine also added a fourth rotor. The Germans also developed increasingly complex operating procedures. Enforcement of these procedures varied. The Luftwaffee was especially lax. Some commanders became concerned that the Allies might be breaking the Enigma codes. As a result, the Germans conducted investigations about this possibility. The German experts concluded, however, that Enigma was still secure. Their assessments proved to be inaccurate. 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 which they turned over to the Britih just before the German invasion launching the War. 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 procedures and the fourth rotar. Many messages were read because operators did not follow procedures. The Royal Navy managed to obtain an intact Enigma machine and associated material needed to set the machines. Decoded 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.

French codes

Italian codes

We do not know a great deal about Italian code systems. We do know that they relied on the German Enigma machines, but were less cautious about security.

Japanese Codes

American cryptologists before World War II broke the Japanese diplomatic codes, first Red and then Purple. The resulting inteligence program became known as Magic. This did not prevent the devestating Pearl Harbor attack. Subsequently American code breakers finally cracked the civeted Japanese naval code-JN-25. This played a key role element in the American naval victory at Midway (June 1942). It also allowed American pilots to shoot down Adnmiral Yamamoto--the architect of the attack on Pearl Harbor. Ironically, Magic proved to be the best source of informatuon outside of Ultra on German operations. Japan and Germany were Axis allies. The Japanese Ambassador to Germany, Osima, was ardently pro-NAZI and wanted Japan to join in Barbarossa. He had very cordial relations with high NAZI officials. He thus obtained and relayed very accurate and detailed messages on to Tokyo about the conduct of the War in Europe. These messages as a reult of Magic were thus available to American officials. Thriugh Magic intercepts, the United States learned of Operarion Barbarossa and were the source of the warning President Roosevelt gave Stalin (without devulging the source) just before the surprise NAZI attack.

Soviet codes

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.

Created: May 30, 2004
Last updated: 4:44 AM 5/2/2009