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HomeHistoryCryptologic HistoryHistorical-EventsArticle View

# The Investigations

On 6 December 1941 a 14-part message was sent from Tokyo to the Japanese ambassador to the United States. The entire message was to be presented to President Roosevelt at approximately the same time as the attack on Pearl Harbor, breaking off relations between Japan and the United States. The fourteenth part of the message arrived somewhat later than the thirteenth. In that same vein, we offer the fourteenth installment of our series on Pearl Harbor.

On 7 December 1941 Japanese naval aircraft swept in on an unsuspecting U.S. Pacific Fleet and Army in the Hawaiian Islands and destroyed many American ships and aircraft. In a little over 2 hours, 18 warships--including 8 battleships--and over 160 aircraft were knocked out of action. Japan's eastern flank secured, its forces would rampage through the rest of the Pacific virtually unopposed.

Within days of the disaster, calls resounded from the public, press, and the government itself for an investigation into how and why such a thing could happen. To many, it was not just the magnitude of the defeat; the extraordinary unpreparedness of U.S. forces in Hawaii seemed almost criminal. Someone had to pay.

However, fixing responsibility for the debacle at Pearl Harbor was complicated by the revelations about the MAGIC decryptions. MAGIC was the covername assigned to the intelligence garnered from the decryptions and translations of Japanese diplomatic messages. From mid-1940 until the attack on Pearl Harbor, American cryptologists had read the most sensitive Japanese diplomatic messages and had kept President Roosevelt informed of every Japanese diplomatic and political policy turn. But MAGIC didn't tell Roosevelt and other government leaders what the Japanese military was planning. Those ciphers and codes had largely resisted the efforts of American cryptologists to break them. Any investigation of the Pearl Harbor disaster would be as much a revelation of what we DIDN'T know as of what we DID know.

The issue of culpability would not be settled in one investigation; in fact, for many people it was never really settled at all. Ultimately, EIGHT hearings would be held over the course of World War II, culminating in a joint congressional investigation beginning on 15 November 1945. What follows is a brief summary of each.

The Roberts Commission, 18 December 1941-23 December 1942:This commission, set by presidential executive order, and chaired by Owen Roberts, a justice of the Supreme Court, was charged to determine the facts of the Japanese attack and establish if any dereliction of duty had occurred. MAGIC was discussed, but who received it and the details of the reports were not covered. Not surprisingly, the hearings were hostile to the area commanders, General Walter Short and Admiral Husband Kimmel. The major political and military figures in Washington were exonerated.

The Hart Inquiry, 15 February 1944-15 June 1944:The Navy Department ordered Admiral Thomas Hart, former commander of the Asiatic Fleet, to conduct a one-man inquiry on Pearl Harbor so that important testimony would not be lost by hazard of war.

The Army Pearl Harbor Board, 20 July 1944-20 October 1944:In response to an act of Congress on 13 July 1944, the army's adjutant general convened hearings which took testimony from 151 witnesses. MAGIC evidence was taken only during the last week of the hearings. Surprisingly, and perhaps because radio intercept information was downplayed, the board censured Generals George Marshall and Leonard Gerow (War Plans Division) for not fully advising General Short of the situation.

The Naval Court of Inquiry, 24 July 1944-19 October 1944:A court of inquiry was convened in response to the same congressional act of 13 July 1944. The hearings made full use of MAGIC, though the testimony on it was classified and kept from the public. The findings of the inquiry completely exonerated Admiral Kimmel. Instead, Admiral Harold Stark, chief of naval operations at the time of Pearl Harbor, was blamed for failing to adequately advise Kimmel of the critical situation prior to the attack.

The Clausen Investigation, 23 November 1944-12 September 1945:By personal direction of the secretary of war, a one-man inquiry conducted by Major Henry Clausen was detailed to obtain testimony to supplement the Army Board's completed investigation.

The Hewitt Inquiry, 14 May 1945-11 July 1945:Similar to the Clausen investigation, the navy secretary ordered Admiral Kent Hewitt to continue the naval inquiry.

The Clarke Investigation, 14-16 September 1944 and 13 July 1945-4 August 1945:The secretary of war ordered Colonel Carter Clarke, head of the Military Intelligence Division, which, in turn, oversaw the army's COMINT efforts, to investigate the handling of communications by the military intelligence division prior to Pearl Harbor.

On 15 November 1945, the Joint Congressional Committee Investigation into the Pearl Harbor disaster held its first session. Established by a Joint Congressional Resolution, this investigation promised to be the most thorough possible. The Truman administration released all of the relevant classified documents, including the MAGIC translations. All of the participants still alive, with the exception of the seriously ill Secretary of War Stimson, were examined. In 1946 the committee's findings were released in forty volumes. A single volume report contained twelve findings that apportioned the blame among all the principals: Hawaiian area commanders and the War and Navy Departments. A minority report also censured Roosevelt but concluded, like the majority findings, that Secretary Stimson, Secretary Knox, Generals Marshall and Gerow, and Admiral Stark, as well as General Short and Admiral Kimmel, were culpable for the disaster.

The hope that the investigations would finally determine who was responsible was never fulfilled. Although many figures in Washington were blamed, Kimmel and Short would bear the onus for the disaster. But the fifty years following the investigations would see a stream of "revisionist" histories and rationalizations for the major figures, such as Admiral Kimmel. Conspiracies to suppress intelligence by Churchill, Roosevelt, and others would be "exposed." Other historians would "discover" new intelligence that existed which would have saved Pearl Harbor. However, the phoenix-like nature of the Pearl Harbor controversy proved only what one of Admiral Kimmel's lawyers wrote to him in 1953: "Pearl Harbor never dies, and no living person has seen the end of it."

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