APPENDIX E
Though it was long kept a secret, the contribution of the code breakers to American victory in the Battle of Midway is now well known. At the center of that story, however, is a continuing mystery about a particular message: the detailed twelve-part Japanese operational order dated May 20 that Joseph Rochefort says he took with him to the meeting with Chester Nimitz on May 25. According to the oral testimony of several cryptanalysts at both Melbourne and Pearl Harbor who claim to have seen it, this message contained the complete Japanese order of battle as well as their prescribed route, the bearing to Midway, and even the timing of the air attack. In many subsequent histories of the battle, this document is credited with giving the Americans the decisive edge against their superior foe and making American victory not only possible but even inevitable.* The problem is that no copy of this intercept has survived.
At least six men later testified that they saw and handled the document. Petty Officer Bill Tremblay, who found it, Lieutenant Commander Gil Richardson, the duty officer at FRUMEL, who sent it on to Hypo, Ensign (later Rear Admiral) Ralph Cook who was at FRUMEL during the effort to break the message, Ensign (later Rear Admiral) Donald “Mac” Showers, and Lieutenant (later Captain) Jasper Holmes at FRUPAC, who worked on it, and of course Commander (later Captain) Joseph Rochefort, who took it with him to his meeting with Nimitz on May 25. It is improbable that all six men should invent such a document and cling to the story of it so consistently over seventy years. Nevertheless, the document itself has never been found. Such a mystery has led some scholars to wonder if it ever existed at all.
Edwin Layton, who was the person in the best position to know, insisted for the rest of his life that no such document ever existed and, moreover, that the code breakers never had the complete Japanese order of battle for Midway. In an interview with Etta Belle Kitchen on May 31, 1970, Layton declared emphatically that “everything that has been written about that is absolutely, unqualifiedly false,” and that “there was no such message.” When Kitchen pressed him, asking “to make it perfectly clear, [that] there never was a complete battle order as it reported in some of the books,” Layton replied: “Never was. Not available to us” (Layton Oral History, 125–27).
Why, then, do so many people remember it? An investigation of the Layton Papers at the Naval War College in Newport, Rhode Island, suggests a possible explanation. Layton kept a personal (and highly confidential) journal during his time as Nimitz’s intelligence officer. The physical journal itself offers insight into the kind of mind that is drawn to cryptanalysis, for it is written in four colors and in tiny—almost microscopic—handwriting; reading it today requires the use of a magnifying glass. In this journal, Layton carefully recorded all the intercepted messages that he considered important each day. There is no record in that journal of a unified twelve-part message on May 20, but it does indicate a dramatic upswing in the volume of message traffic that day. Some of the messages concerned a planned Japanese “fleet exercise,” but a dozen others obviously referred to a forthcoming operation. One revealed the presence of “occupation forces” for both Midway and Alaska. Another mentioned that Japanese forces would approach the target from the northwest. As the Hypo analysts worked on these messages, the results would have been collated and compared so that Rochefort could present the collected findings to Nimitz. Very likely, therefore, the men who achieved this intelligence coup recalled their effort as having focused on a single message rather than a group of shorter messages. If so, instead of one lengthy and detailed operational order, the May 20 decrypt remembered by several of the Hypo analysts and reported in several histories of the battle may well have been a composite of a dozen shorter messages.
Another important correction to the record is that the extent of the detail about Japanese plans contained in these messages has been significantly exaggerated. Though the messages did indicate the presence of four carriers, they did not, for example, specify that they would be operating as a single unit, which had important consequences for the battle. If the Hypo analysts had been able to provide such information, it might have avoided the calamitous “flight to nowhere” on the morning of June 4. Nor did those messages show that Yamamoto himself was at sea with the “Main Body” including the massive battleship Yamato. Though the code breakers at Hypo and Belconnen made a signal and significant contribution to American victory at Midway, they did not provide a detailed blueprint of the enemy’s operational plans, as is sometimes asserted. The decrypts of May 20 were not the equivalent, for example, to the discovery of Robert E. Lee’s famous War Order No. 191, at Frederick, Maryland, on the eve of the Battle of Antietam during the Civil War.
None of this detracts from the crucial contributions of the code breakers, but it does remind us that the subsequent decisions made by the commanders on the scene were more complex and open-ended than might otherwise be assumed. The Battle of Midway was not won by the code breakers alone but by the analysts, the decision makers who trusted them, and finally by the men who drove the ships, manned the guns, and flew the planes at the point of contact. Certainly there is enough glory for all of them.
* This includes my own own book, Decision at Sea: Five Naval Battles that Shaped American History (New York: Oxford University Press, 2005), which acknowledges that the May 20 intercept was a “series of recently intercepted Japanese messages” but attributes to them far more specificity than they actually contained (p. 210).