MAGIC
MAGIC. By the late summer of 1940, American cryptanalysts managed to break some of Japan's most secret diplomatic codes. This remarkable achievement was designated MAGIC. Although American officials frequently used the same cover name referring to later successes against Japanese military and naval codes, which were called ULTRA, the MAGIC operation dealt primarily with Japanese diplomatic communications. The road to the major breakthrough, however, was long and uneven.
In the mid‐1930s, the U.S. Navy concentrated on Japanese naval cryptographic systems while the U.S. Army Signal Intelligence Service (SIS), under the direction of William F. Friedman, tackled Japanese diplomatic codes. By 1935, the SIS managed to crack Japanese diplomatic messages encrypted by the sophisticated “Red Machine,” which was put into use in the early 1930s. The accomplishments of Friedman and his team were short‐lived because in late 1938, the Japanese foreign ministry introduced a new and more secure cipher machine, the “Purple Machine,” for its top‐secret messages. By the spring of 1939, the new Purple Machine replaced much of the Red Machine traffic. As a result, the SIS found that its vital source of intelligence on Japanese intentions and developments dried up completely. Immediately, Friedman and a group of SIS colleagues focused their attention on unraveling this setback. Friedman benefited immensely from the input of his team, including mathematicians, cryptanalysts, and linguists. They worked laboriously for the next eighteen months to solve Purple and also to construct a Purple Machine.
The breaking of Purple was such a daunting and seemingly unachievable endeavor that Brig. Gen. Joseph O. Mauborgne, chief signal officer, referred to the cryptanalysts as “magicians” and to their results as “magic.” From then onward, the codeword MAGIC was given to the solution of Japanese diplomatic messages that were encrypted by the Purple Machine.
After the initial breakthrough in the fall of 1940, the Americans swiftly found that they had access to a huge volume of radio traffic between Tokyo and its diplomatic representatives throughout the world. Cryptanalysts were soon processing fifty to seventy‐five Japanese messages a day. The increase in workload strained the resources of the understaffed SIS. Consequently, the U.S. Army and the U.S. Navy made an agreement to share responsibility for MAGIC whereby the army was in charge of decrypting and translating materials on odd days while the navy was given even days. This arrangement between both services continued until early 1942.
The United States realized that MAGIC provided invaluable insights into the inner workings of the foreign ministry in Tokyo. In order to protect this secret source of intelligence, American authorities adopted stringent security measures for the dissemination of MAGIC reports. Distribution of the highly sensitive materials was intentionally limited to a select group of the highest‐ranking officials. Neither the secretary of state nor President Franklin D. Roosevelt was permitted to retain copies of MAGIC. The army, and the navy later, even took President Roosevelt off the list of authorized personnel for a short time when it was discovered that a copy of MAGIC found its way into the wastebasket of a senior official at the White House.
In early 1941, Friedman and his group managed to recreate several duplicate copies of the machine that enciphered Purple. By the end of the year, eight of these machines had been built. Four remained in Washington (two each for the army and navy), three were given to the British, and one was sent to intelligence headquarters of Gen. Douglas MacArthur on Corregidor Island in the Philippines.
A staggering amount of Japanese messages became available to American intelligence agencies by 1941 because MAGIC included diplomatic communications between Tokyo and all its consular and embassy representatives throughout the world. Given the limited number of personnel, especially experienced linguists, working on this secret program, Washington had to make a choice from among the flood of despatches that were being intercepted. Since crucial negotiations between the United States and Japan were taking place in 1941, priority was given to the Tokyo/Washington circuit. Working under pressure and tight schedules, the MAGIC team of codebreakers made outstanding progress. As the historian David Kahn, a leading authority on code and codebreaking, has noted, from March until December 1941, only 4 messages out of 227 relating to the talks between Secretary of State Cordell Hull and Ambassador Kichisaburo Nomura failed to be picked up by the United States.
MAGIC revealed only what the foreign ministry discussed with its diplomats and what these representatives reported back to Tokyo. Accordingly, the U.S. government did not obtain a complete picture of Japanese military planning, which was often not passed along to their diplomats until matters had proceeded well along course. In fact, the United States had been unable to break high‐level Japanese Army and naval codes until after the attack on Pearl Harbor, especially since each Japanese agency utilized systems entirely different systems from the foreign ministry.
Unexpectedly, MAGIC turned out to be an excellent source of military and diplomatic intelligence on the war in Europe, especially on German plans and intentions. While serving his second tour as Japanese ambassador to Germany from February 1941 to May 1945, Hiroshi Oshima, who had direct access to Adolf Hitler and his closest advisers, sent to Tokyo detailed reports on his conversations with German officials and also his observations while touring the German front lines. Even Gen. George C. Marshall, U.S. army chief of staff, acknowledged privately in 1944 that Oshima's despatches were one of the most important sources of intelligence on Germany during World War II. The United States had forewarning and details of Hitler's planned invasion of the Soviet Union in spring 1941 because of reports from Oshima. Another vital piece of intelligence surfaced in May 1944, when the Japanese ambassador informed Tokyo that Hitler remained convinced that the main Allied invasion of France would take place near Calais and that operations against Normandy were diversionary.
Despite strenuous measures to conceal MAGIC, certain aspects of the operation became public knowledge in late 1945 during the joint congressional investigations into the Pearl Harbor attack. In response to a determined national quest to find blame for one of America's worst military and naval disasters, President Harry S. Truman reluctantly reversed his initial decision and authorized the release of limited MAGIC messages dealing with U.S.‐Japan relations prior to 7 December 1941. The revelation immediately generated sensational headlines and commentaries. No further materials on MAGIC were released until 1977, when the Department of Defense published a five‐volume history of communication intelligence and the Pearl Harbor attack. Since then, the U.S. government has periodically declassified its records on MAGIC and continues to do so.
Ever since MAGIC was made public, historians have drawn upon the vast collection of translated messages to reevaluate certain aspects of American history between 1940 and 1945. These despatches have provided fuel for both proponents and opponents of the theory that the United States had prior warning of the bombing of Pearl Harbor. To this day, no specific evidence shows that there were definite indications within the messages that referred to the Japanese plans for the attack. However, a careful and thorough analysis could have shown that Japan in late 1941 was determined to confront the United States and that plans for an attack on U.S. forces somewhere in the Pacific were underway.
The MAGIC materials have also been used to justify or deny the successful efforts by Japanese Americans during the 1980s to obtain redress from the U.S. government for the wartime internment of Americans of Japanese ancestry. Opponents pointed out that several communications from the West Coast Japanese consulates and the embassy in Washington in 1941 reported that they were attempting to recruit second‐generation Japanese Americans for propaganda and espionage purposes. On the other hand, Japanese Americans have argued that there has never been a documented case of any disloyalty among them.
In recent years, MAGIC intercepts helped fuel the heated controversy over the American decision to order the atomic bombings of Hiroshima and Nagasaki. Indeed, intercepted messages confirmed that the Japanese government was deeply divided over whether to accept the Allied ultimatum for an unconditional surrender. Critics of the bombing emphasized that in 1945, strong elements within the government of Japan desperately sought the mediation of the Soviet Union so that the war could be ended without the termination of the emperor system and the imperial household. Proponents of the atomic bomb, however, suggested that these MAGIC messages indicated that Japan would not have agreed to the unconditional surrender if nuclear weapons had not been used.
In the final analysis, contrary to popular belief, MAGIC did not provide any specific indications of Japan's surprise air attack on Pearl Harbor, nor—unlike the breaking of the Japanese Navy and Army codes in 1942 through ULTRA—did it have any significant impact on operations during the Pacific War.
[See also Coding and Decoding; Intelligence, Military and Political; Japanese‐American Internment Cases; World War II: Military and Diplomatic Course; World War II: Changing Interpretations.]
In the mid‐1930s, the U.S. Navy concentrated on Japanese naval cryptographic systems while the U.S. Army Signal Intelligence Service (SIS), under the direction of William F. Friedman, tackled Japanese diplomatic codes. By 1935, the SIS managed to crack Japanese diplomatic messages encrypted by the sophisticated “Red Machine,” which was put into use in the early 1930s. The accomplishments of Friedman and his team were short‐lived because in late 1938, the Japanese foreign ministry introduced a new and more secure cipher machine, the “Purple Machine,” for its top‐secret messages. By the spring of 1939, the new Purple Machine replaced much of the Red Machine traffic. As a result, the SIS found that its vital source of intelligence on Japanese intentions and developments dried up completely. Immediately, Friedman and a group of SIS colleagues focused their attention on unraveling this setback. Friedman benefited immensely from the input of his team, including mathematicians, cryptanalysts, and linguists. They worked laboriously for the next eighteen months to solve Purple and also to construct a Purple Machine.
The breaking of Purple was such a daunting and seemingly unachievable endeavor that Brig. Gen. Joseph O. Mauborgne, chief signal officer, referred to the cryptanalysts as “magicians” and to their results as “magic.” From then onward, the codeword MAGIC was given to the solution of Japanese diplomatic messages that were encrypted by the Purple Machine.
After the initial breakthrough in the fall of 1940, the Americans swiftly found that they had access to a huge volume of radio traffic between Tokyo and its diplomatic representatives throughout the world. Cryptanalysts were soon processing fifty to seventy‐five Japanese messages a day. The increase in workload strained the resources of the understaffed SIS. Consequently, the U.S. Army and the U.S. Navy made an agreement to share responsibility for MAGIC whereby the army was in charge of decrypting and translating materials on odd days while the navy was given even days. This arrangement between both services continued until early 1942.
The United States realized that MAGIC provided invaluable insights into the inner workings of the foreign ministry in Tokyo. In order to protect this secret source of intelligence, American authorities adopted stringent security measures for the dissemination of MAGIC reports. Distribution of the highly sensitive materials was intentionally limited to a select group of the highest‐ranking officials. Neither the secretary of state nor President Franklin D. Roosevelt was permitted to retain copies of MAGIC. The army, and the navy later, even took President Roosevelt off the list of authorized personnel for a short time when it was discovered that a copy of MAGIC found its way into the wastebasket of a senior official at the White House.
In early 1941, Friedman and his group managed to recreate several duplicate copies of the machine that enciphered Purple. By the end of the year, eight of these machines had been built. Four remained in Washington (two each for the army and navy), three were given to the British, and one was sent to intelligence headquarters of Gen. Douglas MacArthur on Corregidor Island in the Philippines.
A staggering amount of Japanese messages became available to American intelligence agencies by 1941 because MAGIC included diplomatic communications between Tokyo and all its consular and embassy representatives throughout the world. Given the limited number of personnel, especially experienced linguists, working on this secret program, Washington had to make a choice from among the flood of despatches that were being intercepted. Since crucial negotiations between the United States and Japan were taking place in 1941, priority was given to the Tokyo/Washington circuit. Working under pressure and tight schedules, the MAGIC team of codebreakers made outstanding progress. As the historian David Kahn, a leading authority on code and codebreaking, has noted, from March until December 1941, only 4 messages out of 227 relating to the talks between Secretary of State Cordell Hull and Ambassador Kichisaburo Nomura failed to be picked up by the United States.
MAGIC revealed only what the foreign ministry discussed with its diplomats and what these representatives reported back to Tokyo. Accordingly, the U.S. government did not obtain a complete picture of Japanese military planning, which was often not passed along to their diplomats until matters had proceeded well along course. In fact, the United States had been unable to break high‐level Japanese Army and naval codes until after the attack on Pearl Harbor, especially since each Japanese agency utilized systems entirely different systems from the foreign ministry.
Unexpectedly, MAGIC turned out to be an excellent source of military and diplomatic intelligence on the war in Europe, especially on German plans and intentions. While serving his second tour as Japanese ambassador to Germany from February 1941 to May 1945, Hiroshi Oshima, who had direct access to Adolf Hitler and his closest advisers, sent to Tokyo detailed reports on his conversations with German officials and also his observations while touring the German front lines. Even Gen. George C. Marshall, U.S. army chief of staff, acknowledged privately in 1944 that Oshima's despatches were one of the most important sources of intelligence on Germany during World War II. The United States had forewarning and details of Hitler's planned invasion of the Soviet Union in spring 1941 because of reports from Oshima. Another vital piece of intelligence surfaced in May 1944, when the Japanese ambassador informed Tokyo that Hitler remained convinced that the main Allied invasion of France would take place near Calais and that operations against Normandy were diversionary.
Despite strenuous measures to conceal MAGIC, certain aspects of the operation became public knowledge in late 1945 during the joint congressional investigations into the Pearl Harbor attack. In response to a determined national quest to find blame for one of America's worst military and naval disasters, President Harry S. Truman reluctantly reversed his initial decision and authorized the release of limited MAGIC messages dealing with U.S.‐Japan relations prior to 7 December 1941. The revelation immediately generated sensational headlines and commentaries. No further materials on MAGIC were released until 1977, when the Department of Defense published a five‐volume history of communication intelligence and the Pearl Harbor attack. Since then, the U.S. government has periodically declassified its records on MAGIC and continues to do so.
Ever since MAGIC was made public, historians have drawn upon the vast collection of translated messages to reevaluate certain aspects of American history between 1940 and 1945. These despatches have provided fuel for both proponents and opponents of the theory that the United States had prior warning of the bombing of Pearl Harbor. To this day, no specific evidence shows that there were definite indications within the messages that referred to the Japanese plans for the attack. However, a careful and thorough analysis could have shown that Japan in late 1941 was determined to confront the United States and that plans for an attack on U.S. forces somewhere in the Pacific were underway.
The MAGIC materials have also been used to justify or deny the successful efforts by Japanese Americans during the 1980s to obtain redress from the U.S. government for the wartime internment of Americans of Japanese ancestry. Opponents pointed out that several communications from the West Coast Japanese consulates and the embassy in Washington in 1941 reported that they were attempting to recruit second‐generation Japanese Americans for propaganda and espionage purposes. On the other hand, Japanese Americans have argued that there has never been a documented case of any disloyalty among them.
In recent years, MAGIC intercepts helped fuel the heated controversy over the American decision to order the atomic bombings of Hiroshima and Nagasaki. Indeed, intercepted messages confirmed that the Japanese government was deeply divided over whether to accept the Allied ultimatum for an unconditional surrender. Critics of the bombing emphasized that in 1945, strong elements within the government of Japan desperately sought the mediation of the Soviet Union so that the war could be ended without the termination of the emperor system and the imperial household. Proponents of the atomic bomb, however, suggested that these MAGIC messages indicated that Japan would not have agreed to the unconditional surrender if nuclear weapons had not been used.
In the final analysis, contrary to popular belief, MAGIC did not provide any specific indications of Japan's surprise air attack on Pearl Harbor, nor—unlike the breaking of the Japanese Navy and Army codes in 1942 through ULTRA—did it have any significant impact on operations during the Pacific War.
[See also Coding and Decoding; Intelligence, Military and Political; Japanese‐American Internment Cases; World War II: Military and Diplomatic Course; World War II: Changing Interpretations.]
Bibliography
Roberta Wohlstetter , Pearl Harbor: Warning and Decision, 1962.
Ronald W. Clark , The Man Who Broke Purple: The Life of Colonel William F. Friedman, Who Deciphered the Japanese Code in World War II, 1977.
U.S. Department of Defense , The “Magic” Background of Pearl Harbor, 1977–78.
Ronald Lewin , The American Magic: Codes, Ciphers and the Defeat of Japan, 1982.
Carl Boyd , Hitler's Japanese Confidant: General Oshima Hiroshi and MAGIC Intelligence, 1941–1945, 1993.
David Kahn , The Codebreakers: The Comprehensive History of Secret Communication from Ancient Times to the Internet, 1996.
Pedro Loureiro
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