In September 1944, a little known event took place that almost changed the course of the presidential election between Franklin D. Roosevelt and his Republican challenger, Thomas Dewey. More important, perhaps, it might have ended FDR’s administration. The incident involved the covert war against Japan and the most deeply held secrets of the American intelligence establishment.

In 1944 Roosevelt was nominated by the Democratic Party to run for an unprecedented fourth term as president. He had taken office in 1932 when the country was in the midst of the Great Depression. His response to the national crisis had been to create high-profile government works projects such as the National Recovery Act and the Civilian Conservation Corps, to devise new banking laws and a Social Security system that guaranteed funds for retired workers, and to support a massive infrastructure construction and improvement effort across the country. But the Depression was so deep that it took the United States’ entry into World War II following the Japanese attack on Pearl Harbor of December 7, 1941, to finally end it.

Although he had accomplished a great deal in peace and war, FDR’s first three terms had taken their toll. As he prepared to run his fourth race, his health was failing, a fact he kept from the American people. Suffering from an increasingly serious heart condition, the president pushed himself during the campaign against Dewey.

A Columbia University graduate, Dewey had been appointed attorney for the southern district of New York in 1933, and gained a reputation as a crime fighter, going after notorious mobsters such as Dutch Schultz. His well-publicized success against organized crime figures led to his election as district attorney for New York City and, in 1942, governor of New York. In 1944 Dewey was the Republican Party’s rising star.

A great deal had happened since the United States entered the war. The Allies had regained the initiative and three years later were driving the Axis back on all fronts. With the threat of defeat largely past, Americans began to reflect on what had transpired thus far. After the Japanese attack at Pearl Harbor, the government began inquiries into the intelligence failures surrounding it. Congress, the Army and the Navy conducted their own separate investigations. Anti-Roosevelt forces sought to blame the president for the lack of intelligence preceding the Japanese strike. Some went so far as to accuse the president of deliberately letting his guard down at Pearl Harbor in order to bring the United States into the war.

In September 1944, Dewey was speaking out regarding Roosevelt’s conduct of the conflict. Talk around Washington was that he was going to make a major speech in which he would reveal information on the Pearl Harbor attack that would hurt the president. Somehow, Dewey had been made aware of certain classified information regarding the American breaking of the Japanese “Purple Code,” which was used to send secret information between Tokyo and Japan’s embassies around the world.

The fact that the Purple Code had been broken was a highly guarded secret of the war. Armed with Purple intelligence, on December 6, 1941, American officials were able to decipher the crucial 14-point letter from Tokyo to Ambassador Kichisaburo Nomura in Washington, addressing the state of relations between Japan and the United States. When Roosevelt read the letter, he told his confidant Harry Hopkins, “This means war.”

As election day neared, the question was whether Dewey was going to blow the cover on Purple intelligence to promote his own political aspirations. People within the Roosevelt administration worried about what the release of the information would do to the war effort as well as to the presidential campaign. They also wondered what their response should be in the event of such a revelation.

Some of Roosevelt’s associates decided to take the bull by the horns. Without the president’s knowledge, they contacted the Dewey campaign. The point man in the communication was chief of staff and presidential confidant General George Marshall, who had received information about Dewey’s plans for his upcoming speech.

On September 25, Marshall ordered Colonel Carter Clarke, who worked in the War Department’s Division of Military Intelligence Service, to meet with the campaigning Dewey in Tulsa, Okla. Clarke was to travel in civilian clothes and hand-deliver a letter to Dewey and no one else.

The first person Clarke met from the Dewey camp was William Skelly, an oil executive and the Republican candidate’s campaign manager. Skelly demanded the name of the person who had sent Clarke. Reluctantly, Clarke complied and identified Marshall. He then was taken to Dewey and delivered the general’s note.

When Dewey opened the letter, he noticed “Top Secret” stamped at the top of the page and remarked flippantly, “That’s really top, isn’t it.” He proceeded to read the note and told Clarke that he did not want his “lips sealed” on things that he already knew about Pearl Harbor, about facts already in his possession or about facts that might later come into his possession from sources that were mentioned in Marshall’s letter. He was concerned that if he gave his word on the letter, his lips would effectively be sealed.

Dewey then asked Clarke why both General Marshall and Admiral Joseph King, the chief of naval operations, who had been briefed on the Dewey matter, were, in his opinion, the only people in the War Department who had information regarding the letter that Clarke had delivered to him. “Why,” asked an incredulous Dewey, “should the representatives of the president of the United States, especially during an election year, contact an opposition candidate? Marshall does not do things like that. I am confident that Franklin Roosevelt is behind this whole thing.”

After glancing again at the letter, Dewey went on to say: “I have not reread [this] because my eye caught the word ‘cryptograph.’ Now if this letter merely tells me that we were reading certain Japanese codes before Pearl Harbor and that at least two of them are still in current use, there is no point in my reading the letter because I already know that.” The governor then told Clarke that FDR should be impeached. If Clarke had thought he was going to find a receptive audience in the Republican presidential candidate, he was deeply disappointed.

Dewey ended their conversation by bluntly telling Clarke that he was returning to Albany, N.Y., and that he would be interested in meeting with either Clarke, Marshall or a suitable representative sent by the general.

Marshall wrote a second letter to Dewey and sent Clarke to deliver it in Albany. The note requested that Dewey not reveal any information not already in his possession. Clarke arrived on September 28 and was confronted by Elliot Bell, the New York superintendent of banks, who demanded to read the note. The matter was eventually resolved when Dewey called Marshall and requested that Bell be allowed to read the note.

Clarke was then treated to a lecture by Bell, who said he had received firsthand information that Navy officials in the Pacific theater knew for a fact that intercepted Japanese intelligence had made the 1942 American victory at Midway possible.

Bell’s tirade over, Dewey read the second letter, dated September 27. It was detailed and contained top-secret information known to only a few members of the administration. Marshall emphasized once again that only he, Admiral King and a few select others in government knew about this communication between the two camps. Roosevelt had no knowledge of the correspondence and Secretary of War Henry Stimson also had been kept out of the loop.

What Dewey then read was some of the most highly classified information the U.S. government possessed. “In brief,” Marshall wrote, “the dilemma is this”:

The most vital evidence in the Pearl Harbor matter consists of intercepts of the Japanese diplomatic communications. Over a period of years our cryptograph people analyzed the character of the machine the Japanese were using for encoding their diplomatic messages. Based on this, a corresponding machine was built by us which deciphers their messages. Therefore, we possessed a wealth of information regarding their moves in the Pacific, which in turn, was furnished the State Department—rather than as is popularly supposed, the State Department providing us with the information—but which unfortunately made no reference whatever to intentions towards Hawaii until the last message before December 7th, which did not reach our hands until the following day, December 8th.

Now the point to the present dilemma is that we have gone ahead with this business of deciphering their codes until we possess other codes, German as well as Japanese, but our main basis of information regarding Hitler’s intention is obtained from [Japan’s ambassador to Berlin] Baron [Hiroshi] Oshima’s messages from Berlin reporting his interviews with Hitler and other officials to the Japanese Government. These are still in the codes involved in the Pearl Harbor events.

To explain further the critical nature of this set-up which would be wiped out almost in an instant if the least suspicion were aroused regarding it, the battle of the Coral Sea was based on deciphered messages and therefore our few ships were in the right place at the right time. Further, we were able to concentrate our limited forces to meet their naval advance on Midway when otherwise we almost certainly would have been some 3,000 miles out of place. We had full information of the strength of their forces in that advance and also of the smaller force directed against the Aleutians which finally landed troops on Attu and Kiska.

Operations in the Pacific are largely guided by the information we obtain of Japanese deployments. We know their strength in various garrisons, the rations and other stores continuing available to them, and what is of vast importance, we check their fleet movements and the movements of their convoys. The heavy losses reported from time to time which they sustain by reason of our submarine actions, largely result from the fact that we know the sailing dates and routes of their convoys and can notify our submarines to lie in wait at the proper points.

You will understand from the foregoing the utterly tragic consequences if the present political debates regarding Pearl Harbor disclose to the enemy, German or Jap, any suspicion of the vital sources of information we possess.

After describing some secret operations carried out by Bill Donovan’s Office of Strategic Services against the Japanese, Marshall ended his letter: “I am presenting this matter to you in the hope that you will see your way clear to avoid the tragic results with which we are now threatened in the present political campaign.”

If, after reading Marshall’s more detailed second letter, Dewey had any inclination to divulge its contents, he quickly put it aside. Good, patriotic citizen that he was, the New York governor put the nation’s interests ahead of his own and kept his lips sealed.

It is now known that Harry Hopkins told the president shortly before the election what Marshall had done. Roosevelt never reproached Marshall.

On November 7, 1944, Roosevelt was reelected to his fourth term in office. It was not until a year later that the public was informed of the secret Dewey-Marshall correspondence and by then the point was moot—Roosevelt was dead and the war was over.

The impact on Dewey’s campaign of his decision not to give away the secret of Purple will never be known. The fact that the secret was kept, however, may have saved countless lives. Marshall had taken a huge risk in approaching Dewey, and the Roosevelt administration was lucky that he chose to remain silent. In the final analysis, patriotism in time of war was more important than politics, even to a presidential candidate.


Originally published in the April 2006 issue of World War II. To subscribe, click here