Live Ammo
A blizzard of events followed the sneak attack at Pearl Harbor that had implications for Rochefort’s Station Hypo and, by extension, for the entire fleet. Up until December 7, 1941, Rochefort, Dyer, and the rest of the crew had been knocking their heads against the wall of the Japanese flag officer’s code, an extraordinarily complex cipher that task force commanders used to communicate between themselves and headquarters back in Japan. Beyond the complexity of the code itself, the code breakers were further hampered by the fact that the Japanese seldom used the code. Without a sufficient amount of traffic, they didn’t have enough examples to see patterns repeating, and as far as we know, the solution has never been solved.* After Pearl Harbor, the Navy department in charge of decryption, OP-20-G, directed Hypo to abandon the flag officer’s code and start work on another code, JN-25. Unlike the flag officer’s code, the Japanese used JN-25 frequently and had sufficient confidence in its security to transmit a huge amount of crucial information. By war’s end, they had sent about 70 percent of their traffic in this code.
Another result of the sneak attack was a conspiratorial air of recrimination about who was responsible for the catastrophe. Although Japan’s aircraft carriers effectively ruled the entire ocean long before they even lifted anchor on a course for Pearl Harbor, the prevailing attitude in the United States among sailors and civilians alike was that sufficient warning would have somehow averted the disaster. The Navy looked to radio intelligence with renewed interest, and when Rochefort requested more personnel and more space in the Administration Building to put them, he generally got whatever resources were available. When the USS California sank at Pearl Harbor, the ship’s band no longer had a ship to play for—or any instruments to play with—so the district commandant assigned them to Hypo. Their abilities as musicians translated well into their new work as code breakers, and despite a wrongheaded attempt to wrest them from Hypo that went all the way to Admiral Kimmel’s legendary replacement, Admiral Chester Nimitz, the unlikely “crippies” (cryptographers) stayed there and made significant contributions throughout the war.
Jasper Holmes had been delivering radio traffic summaries to the CincPac (Commander in Chief, Pacific) offices since November, and when subs began leaving for patrols in the mysterious Japanese-held Marshall and Caroline islands in December, the sub captains came to him for whatever little information he could provide for upcoming patrols. He was also briefing the submarine command about ship positions with his charts every morning. Now the collaboration with his old buddies in the sub force started to develop into what was perhaps the single most effective and devastating tactic against the Japanese navy. Since the onset of hostilities, Rochefort and Holmes had been watching the positions of Japanese submarines. The sub captains often betrayed their positions by shelling American land bases with their deck guns before the end of a patrol and were often very chatty in their radio broadcasts. In a technique called direction finding or DF, two or more Navy radio receivers at different locations would pick up the direction of these broadcasts, and determine their location by triangulation. Holmes tracked the Japanese sub I-173 across the Pacific as it shelled San Diego, then Midway. ComSubPac Tommy Withers got word that a Japanese submarine would probably be intersecting the path of the submarine USS Gudgeon at a particular point on January 18, 1942, but Holmes almost certainly didn’t tell Withers that they’d derived that from radio intelligence, or that the I-173 had been broadcasting frequently along the way.
To his credit, Withers took the chance, and skipper Joe Grenfell of the Gudgeon described the ship when it miraculously came his way as “fat, dumb, and happy . . . the men were lounging on the upper deck, sunbathing and smoking.” Grenfell fired three torpedoes, but this upset the trim of the boat and he was unable to see what happened while his periscope dipped under the water. He heard an explosion, then silence. When he was able to get another look, the I-173 was gone, and he guessed that they may have dived with the ports open, sinking their own boat. Whether this was the case or the torpedo sank them was now academic, because their daily broadcast was never heard again, and the Japanese navy ceased references to the ship.
The code breakers had also broken a minor code that had major implications. The Japanese navy amassed at Truk in the Caroline Islands and so Truk came to be known as Japan’s “Gibraltar of the Pacific.” The port director there broadcast announcements about the departure of ships and convoys, as well as their noontime positions as they followed a strict, prescribed path to their destinations. Rochefort may not have believed his great fortune in discovering the names, destinations, and exact courses of enemy ships from this important port. Holmes immediately recognized that it would give the submarine skippers great chances for prize targets, instead of roaming the vast Pacific looking for opportunities. In this instance, however, there was no way for Holmes to conceal how they’d come by the information. There were no coast watchers that far into the Pacific. No spy could transmit the comings and goings of ships from Truk with sufficient broadcast strength to go undetected by the Japanese. The sub commanders would get the information firsthand if it had come from a stealthy submarine; they would naturally conclude that the only way for the deskbound oddballs in Hypo to have gotten such explicit information was for them to have broken a Japanese code. When Holmes caught wind that the heavy aircraft carrier Shoho was coming out of Truk, he had no doubt that the submariners could be trusted, but Rochefort was skeptical.
What Holmes proposed was extremely risky business. It was strictly forbidden by the guidelines for the use of radio decryption intelligence; it could not be used for minor tactical advantages, even if it was as significant as the aircraft carrier Shoho. The logic was that if the Japanese carriers suddenly had American submarines along their paths wherever they went, they would become suspicious, perhaps change the code, and leave the Americans in the dark when they most needed that source of intelligence. But as Tom Dyer said, battles are won on the basis of minor tactical advantages. Rochefort relented, but gave strict conditions: No paper was to leave the office, and Holmes would have to lie if the officers at ComSubPac questioned him closely.
In the first of a series of surreptitious intelligence tips, Holmes took a fountain pen and wrote on his palm the map coordinates where the paths of the carrier Shoho and the submarine USS Grayling would overlap. After divulging this to his old submariner friend Charles “Gin” Styer, Withers’s chief of staff, he washed his hands thoroughly with soap and water. Styer took the information seriously and didn’t inquire too closely about its provenance. The skipper on the Grayling went to the coordinates on February 18 and followed the orders to remain submerged during the day while his soundman monitored for the Shoho. Unfortunately, he stayed too deep for periscope observations, and neglected to load the tubes in time for an attack when he got a report of heavy screws. As a result, he watched the prized target slip away.
When ComSubPac read the skipper’s patrol report, they recognized that the opportunity for a contact with such exacting detail would never have developed without Holmes’s information, and came to think of the instance as a bird in the hand that had somehow gotten away. In his official reaction to the patrol report called “endorsements,” Tommy Withers proceeded to figuratively flay the skipper alive.
While it’s true that the Grayling may have had a better chance of firing on the Shoho if the skipper had taken different actions, the officers at Pearl who were disappointed when decryption possibilities didn’t always translate into sinkings would discover that intercepting ships in the Pacific, as in this case, would always be a tricky business. The torpedoes had an effective range of about 2,500 yards; anything beyond that made the shot much more difficult. In order to get within 2,500 yards, the sub had to spot the target early and maneuver into position, often eluding dangerous destroyer escorts in their path. If they made contact during the day, the sub would have to do this underwater, where the subs were significantly slower. While a carrier or battleship regularly clipped along at 25 knots, a U.S. fleet boat could go only about 8 knots underwater for a half hour before its batteries were depleted. Usually it would lurk at about 2 to 3 knots to conserve its batteries for the time when it might get depth-charged—a certainty if it fired on a ship or convoy with escorts. Even the stars had to be aligned in order for any of these contacts to develop, because both navies navigated with celestial observations. If a storm was brewing up for a couple of days before a contact, the sub might not have a good celestial reference to fix its exact position. The same was true for the navigators on the target ships, and a navigation inaccuracy on the submarine compounded by an inaccuracy on the other ship could put the enemies so far away from each other at the appointed time that they might never see each other.
Despite the many frustrations, the submarine force recognized that what Holmes gave them was gold—wherever it came from—and coordinated their plans with him whenever possible.
During this time, the government was evacuating the dependents of military personnel from the Hawaiian Islands, just as they had in the Philippines before the war. For Rochefort’s and Holmes’s friend John Cromwell, as well as for countless others, it meant separation from their families, sometimes forever. Like many submarine families, the Cromwells moved to the familiar territory of Palo Alto, California. It was close enough to San Francisco to be accessible to the Mare Island Navy Yard, where the Navy built and overhauled submarines, but far enough to be—at that time—less expensive than San Francisco. For John Cromwell’s son, Jack, and daughter, Ann, this meant new schools, a new neighborhood, and growing up without their father. Adding more strain to the situation was the presence of Margaret Cromwell’s parents, who had moved in with them at their home in Palo Alto. Their grandparents had fallen on hard times during the Depression and, with the onset of old age, found it difficult to find jobs and support themselves.
While the family strained to hold itself together, Jack tried to take on the responsibility of being the man of the family—an unbidden role he tried his best to fulfill, for the time being anyway. Many of his new schoolmates found themselves in similar circumstances—an age of bubblegum and comic book heroes, of afternoon radio serials and matinees at the Bijou. Newsreels like The March of Time struck people differently in that time of intense patriotism; it seemed that those who had no family in the war thought of individuals’ sacrifices with a detached, almost uncomprehending mien. Nevertheless, the propaganda spurred people on to join the armed services, buy war bonds, make Victory Gardens, and recycle war materials like steel cans and tires. They also swallowed tax increases as well as the rationing of nearly everything: gasoline, meat, butter, even bread. It didn’t matter how much money you had—if you didn’t have the coupons to buy certain commodities, you just couldn’t buy them. The newsreels were persuasive, shocking, effective, and for those who did have family members on the front lines, they were frightening. Young Ann Cromwell frequently cried.
Back in Hawaii, the military couldn’t enforce the evacuation among personnel with families classified as residents, who owned homes and paid mortgages, like Holmes and Dyer. The families who decided to stay found their social lives suddenly truncated as many of their civilian friends moved back stateside and the Navy built Pearl Harbor back, bigger even than anyone had ever imagined. Honolulu and the surrounding area also went through major changes as the Hawaiian Islands became the key staging area for fleet movements and invasions. Despite having the comforts of home, due to the nature of his decryption work Dyer would leave home with a lunchbox full of sandwiches his wife packed for him, and wouldn’t return for days at a stretch, until he ran out of food or Rochefort ordered him to take a break and get lost for a couple of days.
All of them worked around the clock in the basement, sometimes sleeping fitfully on cots in the hallways for a few hours like college students cramming for a test. But the consequences of their test were literally a matter of life and death, and as the cryptographers grappled with the befuddling nuances of the JN-25 code, the cool, dank atmosphere in the basement of the Administration Building took its toll in the form of colds that often developed into pneumonia. Rochefort seldom left the building and took to wearing a red smoking jacket and carpet slippers, which gave rise to the legend that he was a bizarre eccentric. While this attire may not have been strictly Navy regulation and it was true that he had a strong personality that sometimes got him in trouble, he was by no means an eccentric. The mad professor aura created by the smoking jacket and carpet slippers was really just a pragmatic attempt to keep warm, but somehow it stuck and he is remembered that way in books and films. He was, on the other hand, a very dedicated commander who marshaled his forces to the point of exhaustion but no further. He gave them considerable latitude and loyally backed them up in bureaucratic dustups while he and his crew were accomplishing a half year’s work in a matter of weeks.
The initial break on JN-25 came from Lieutenant Rudolph J. Fabian, a cryptologist at the Navy’s radio intelligence unit at Corregidor (code name Cast) in the beseiged Philippines. The main OP-20-G headquarters in Washington, D.C., also called “Negat,” worked on the codes as well, but it was Rochefort’s group that was able to make most of the breaks.
Coding is the substitution of a letter, word, number, or concept with an unrelated signifier. For instance, we could code the letters a, b, c, t, and u as a=APPLE, b=BALL, c=CHARLIE, t=TOP, u=UNICORN. Working backward, the decode for BALL-APPLE-TOP would be the word “bat.” If the coding is randomized, the code becomes more secure. For example, the sender and receiver of a code may agree to shift the letters in the code up a value of one on a predetermined day. In that case, a=BALL, b=CHARLIE, t=UNICORN, and the decode for CHARLIE-BALL-UNICORN would be the word “bat.” This method is somewhat less intuitive than the original code, and would be slightly more difficult for an amateur. But it is susceptible to a trained cryptologist because of the similarity in values between “a” (apple/ball) and “b” (ball/Charlie). A skilled cryptologist will immediately recognize the pattern using innate skill, mathematical analysis, and intuition to “attack” such a code and break its secrets.
The way to get around this security problem is to use encryption, which is distinct from encoding. The simplest encryption is to substitute letters or words for numbers (encoding), then manipulate the numbers in some way to obscure their meaning (encryption). For instance, we might encode the alphabet thus: a=1, b=2, c=3, and so on. Then we might encrypt it by squaring the numbers in the code: a=12=1, b=22=4, c=32=9, and so on. Therefore, the decrypt of the cipher text 9-1-4 would be the square roots of the sequence, 3-1-2, and the decode of 3-1-2 would be the word “cab.”
The encryption, or scrambling, of the numbers could be quite elaborate. However, given enough examples of a certain code, an astute cryptographer can divine even elaborate computations because they betray themselves by repeating a certain pattern. Overly complicated computations were also undesirable for two other reasons: In the days before computers, doing these calculations by hand would be more prone to error, and their unwieldiness made them too time-consuming. The Germans got around this by using a combination of electrical and mechanical randomness settings on a machine called Enigma. Enigma could be described as an analog computer to automate the encryption and decryption of signals, and used a series of rotors that rotated around a common axis. Essentially, it was a series of magic decoder rings, and each successive ring made the encryption exponentially more difficult to decrypt. A cryptographer trying to break the code would need not only an Enigma machine, but also the initial rotor settings and plugboard settings in order to read the same text as the recipient.
All of this increased the complexity of the encryption and the apparent randomness, and it decreased the amount of work to encrypt and decrypt. Enigma was, however, a machine that repeated certain patterns. Every rotor was wired to scramble in a certain, discrete way, and the Enigma machine’s Achilles’ heel was that the subsequent rotors relied on the motion of the first one, in what was a very predictable pattern. With initial help from expatriate Polish code breakers about the design of the Enigma machine, the British code breakers at Bletchley Park were able to discern those patterns. The British created a method to reduce the number of possible permutations, thereby eventually cracking the code. The Americans mechanized this attack method to determine the initial rotor and plugboard settings, and began decrypting Enigma transmissions in earnest.
In popular culture, the Germans get much credit for using such a diabolically clever device, and the British get even more for cracking its codes. It is interesting to note that the brilliant cryptographer William Friedman in the U.S. Army’s Signals Intelligence Service (SIS), had a similar, though superior, concept at about the same time. Friedman added more rotors and also recognized the vulnerability of the rotor stepping mechanism, so he added a feature that stepped the rotors in a somewhat more random pattern.* The machine he created was called the SIGABA, and the Navy’s version was called the ECM-2. At the beginning of the war, submarines like the Sculpin had to observe the “hundred fathom curve,” a line they could not cross in enemy territory because if the sub sank in anything shallower than a hundred fathoms, or 600 feet, it could conceivably be salvaged, thereby compromising the ECM-2’s secrecy. Fortunately, its code was never broken during the war, and was only retired in 1959, when faster alternatives became available.
In the 1930s, Friedman’s team also cracked the Japanese diplomatic code they called Purple. Years before, the cryptologists went the simplest route when a rapid solution was desired: They cheated by stealing a copy. The SIS had the FBI perpetrate a black bag job—essentially cat burglary—at a Japanese diplomatic office to get the Japanese diplomatic codes. The FBI photographed the codebooks and replaced them without the diplomatic staff suspecting anything. A former missionary to Japan undertook the painstaking translation of the code, and while he did he kept it in a red binder, so the code became known as the Red code. The precedent having been set, subsequent codes were also referred to with color designations: Jade, Coral, and eventually Purple.
Like Germany’s Enigma and America’s ECM-2, Purple was transmitted by an encryption/decryption device that the Japanese called the Type 97. It used stepped rotors, but rather than using rotors with twenty-six steps for the twenty-six characters in the alphabet, it used two ten-step rotors for the consonants and a six-step rotor for the vowels A, E, I, O, U, and Y. This added a level of complexity that proved difficult to solve. Nevertheless, the underlying patterns betrayed the machine’s vulnerability, and the code breakers at SIS were able to ascertain the patterns and break the code. Going one step further, and with the help of SIS cryptographer Leo Rosen, Friedman built a Purple machine so that they wouldn’t have to decrypt each message by hand. To start with an unintelligible string of characters and end with a machine to turn them into intelligence gold was a remarkable achievement. Sadly, the strain and long hours of breaking Purple and making a machine took its toll on Friedman, and after having given so much to protect his country, he had a nervous collapse. He recuperated somewhat and would continue to contribute, but only in a reduced capacity for limited hours.
The Imperial Japanese Navy had a far more difficult system. JN-25, the code Rochefort’s Hypo worked on after Pearl Harbor, was a superenciphered code. To send and receive messages, an operator needed three books. The first was an encoding book, which had up to 33,333 words, concepts, letters, numbers, names, and place-names. Next to each of these was a random five-digit number. All the five-digit numbers were divisible by three, so that if a telegrapher made an error, or the atmospheric conditions garbled the radio reception, a recipient could check to see if the code number corresponded to anything in the codebook.
Let’s say for example that you wanted to encode the sentence “Sam went home.” We would look for the three individual words in the encoding book and write down the five-digit numbers associated with those three words. For simplicity’s sake, let’s say those numbers are 00003, 00006, and 00009, so the encode of “Sam went home” would be 00003-00006-00009. We could broadcast that over the radio with Morse code to our intended recipient, and upon receipt, he would see that each of the three numbers is divisible by three—so it would appear that there are no garbles. The recipient would then take out his decode book, which was essentially the codebook arranged by number instead of by word, like a reverse phone directory. He would look up those three five-digit numbers, finding “Sam,” “went,” and “home.”
Although there are 33,333 possible permutations in such a five-digit code, this was still a simple substitution code. Originators would find themselves using common words over and over again like “fleet,” “destroyer,” or a major port like “Yokohama.” To make it more secure, the Japanese used an additional layer of encryption, making it superenciphered. In addition to the encode book and the decode book was an additive table book, or encryption book. Each page in the encryption book had a page number. On each page you would find several tables. Each table had its own number. Within each table there were numbered columns and numbered rows. In each cell was a random five-digit number.
The process started with a message. Let’s continue with the “Sam went home” example. We would then go to the separate additive table book and randomly choose a starting point on a specific page, in a particular table, column, and row, where we would find a random five-digit number. Let’s say there are ten tables on each page. We pick page 56, and settle on table 3, which looks like this:
Table 3
| 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | |
|---|---|---|---|---|---|---|---|---|---|---|
| 0 | 61725 | 44177 | 58038 | 60558 | 50245 | 35279 | 75326 | 57152 | 60781 | 32871 |
| 1 | 24421 | 43472 | 19331 | 35161 | 35662 | 99586 | 05258 | 88009 | 65366 | 00706 |
| 2 | 33648 | 16881 | 87551 | 76998 | 56197 | 89418 | 25906 | 81003 | 12255 | 87165 |
| 3 | 00744 | 58399 | 69659 | 55314 | 02657 | 70861 | 92033 | 90658 | 02786 | 02896 |
| 4 | 82581 | 94488 | 31838 | 47703 | 50134 | 15460 | 98016 | 10639 | 68894 | 03714 |
| 5 | 81421 | 34784 | 71004 | 75008 | 17325 | 61126 | 93423 | 14128 | 58082 | 71472 |
| 6 | 42264 | 14891 | 47821 | 09803 | 59263 | 63155 | 24614 | 87610 | 21440 | 12120 |
| 7 | 59203 | 21153 | 78483 | 42214 | 03747 | 09652 | 75843 | 38765 | 47655 | 62315 |
| 8 | 00951 | 38126 | 88656 | 38976 | 59146 | 15086 | 24759 | 07842 | 61743 | 40173 |
| 9 | 40867 | 87881 | 66401 | 37593 | 23358 | 28619 | 50212 | 48193 | 78053 | 18233 |
Now we pick a random spot in the table, let’s say column 0, row 3, where we see the number 00744. We subtract this from our first number using Fibonacci subtraction, where subtractions from numerals greater than 10 do not affect the next column. Thus, 00003 (“Sam”) minus 00744 becomes 00369. We move to the next one in the column, 82581, and subtract that from 00006 (“went”), getting 28525. The next number in the column is 81421. We subtract that from our coded 00009 (“home”) and get 29688. The result is 00369-28525-29688. We would send this superenciphered message to the recipient, along with the additive information they’ll need to “strip” the additive from the original coded message (remember, page 56, table 3, column 0, row 3). You could transcribe this as 56303 perhaps, and to be really tricky you could prearrange to make the encryption key the third number in any message you send out, making the message 00369-28525-56303-29688.
The recipient would get this, look up page 56, table 3, column 0, row 3 in his additive book, and using Fibonacci addition (where sums in one column greater than or equal to 10 do not carry over into the next column) add the series of numbers he’d find there, resulting in 00003, 00006, 00009, which he would then look up in his decode book and again find that “Sam went home.”
Any cryptographer, or crippie, getting far enough on his or her own to nail a meaningful number of keys would have to be inspired. It has been said that a good cryptographer either has the soul of a Beethoven and the mind of an accountant or, conversely, the mind of a Beethoven and the soul of an accountant. Making any sense of JN-25 required a breathtaking amount of work, a persevering spirit, and traces of genius. Beyond the thicket of additives and their underlying codes, however, was yet another barrier to understanding JN-25: the subtle intricacies of the Japanese language, and the refined nuances of the culture.
All languages are preliterate; that is, the words for nouns, verbs, adjectives, adverbs, conjunctions, articles, and so forth are conceived and operate in a governing grammar structure peculiar to that language before the language’s users devise a graphical representation—writing, literacy—to actually write those words down. Westerners use alphabets with characters that represent individual sounds, for example the Roman and Cyrillic alphabets. Japanese, on the other hand, can be written with four different, complementary systems. Romaji was introduced by Portuguese missionaries, and is based on the Roman alphabet. The Purple machine used romaji to encrypt and decrypt messages. Katakana (or kana) and the complementary hiragana are both syllabary “alphabets,” that is, each character signifies a syllable. If for example the Japanese language adopted the English word “imprecise,” it would be written with three characters that represent the three syllables in that word: “im,” “pre,” and “cise.” Kanji are characters that were adopted from Chinese ideographs, usually with the original Chinese meaning intact, but with a Japanese pronunciation that sometimes varied greatly from the Chinese; each ideograph represents a full word. Just as word placement or punctuation can alter the meaning of a sentence in the English language, kanji characters can have multiple meanings depending on the context within the sentence, how the characters are combined to create compounds, the character’s placement in the sentence, and other factors.
Suffice it to say that the net effect of all these methods—romaji, katakana, hiragana, and kanji—as well as the intricate rules governing them, and the fact that they are used to transcribe a complex, subtle, and refined language, makes Japanese difficult in the extreme for the uninitiated Westerner. Superenciphering 33,333 terms in this language made JN-25 a howling conceptual wilderness for any cryptographer. It would be no leap of the imagination to surmise that Joe Rochefort, Tommy Dyer, and Ham Wright had photographic memories that could recall the remotest clues of context and syntax in a stack of unrelated messages. It would appear to be the only way for them to have linked the occurrence of one five-digit string of numbers to another in different messages, and recognize the meaning of that word as distinct from any of the other 33,332 words in the code. In Japanese. This was their collective and individual genius.
We’ll examine one final example to illustrate the daunting task that Rochefort’s group undertook. One of the crippies stripped the additive off a message, and its context suggested what he thought might be a place-name. Jasper Holmes’s merchant ship plotting had given him a thoroughgoing knowledge of place-names from around the Pacific, and although he didn’t speak or learn Japanese, Holmes taught himself katakana. The crippie gave him this (or something like this):
Using a katakana table, Holmes learned that these syllables were wou-du-ra-ku. Holmes stared at this for hours. Japanese often place a long “u” sound at the end of foreign-sounding words in the same way that English speakers naturally add an “n” at the end of the article “a” when the following word starts with a vowel, as in a(n) orange; it just sounds right to the Japanese ear. Removing the “u”s from wou-du-ra-ku gives you wo-d-ra-k. Japanese also simply does not have the letter “l,” and native Japanese speakers sometimes pronounce “l” as “r,” for instance the word “lollipop” might be mispronounced “rorripop.” If we take wo-d-ra-k and change the r to an l, we have wo-d-l-ak. Further, if a Japanese language student studied English from a Briton, he might interpret “Woodlark” Island as “Woodlahk,” and pronounce it “WOUDuraku.”
It’s important to keep in mind that this was only one term out of tens of thousands, representing hours of work in an understaffed unit that had the responsibility of informing the entire Pacific Fleet how to conduct the war in the Pacific. The task and responsibility was enormous; if Rochefort got even a minor but crucial detail wrong, the consequences would be catastrophic. If the Imperial Japanese Navy got conclusive evidence that the Americans had broken its codes, the Naval General Staff could have taken any number of steps, any one of which could have led to colossal losses of Allied ships, sailors, soldiers, even its forward bases such as Midway or Hawaii. They could change the additive tables or even the entire code, ruining months of work and leaving Rochefort, Layton, and Nimitz in the dark. The Japanese could also lay a trap. Before Pearl Harbor, the Naval General Staff had taken steps to transmit misinformation indicating that the Kido Butai was in the Sea of Japan, when in fact it was steaming eastward under radio silence with sealed orders to attack Hawaii. The Imperial Fleet by no means lacked the subtlety to lay a trap for the U.S. Navy’s remaining carriers.
If the Allied losses piled up as quickly as they had in the war thus far—already with tens, perhaps hundreds of thousands of military and civilian casualties as well as POWs—the U.S. Navy would have no bases to fight from, and no ships or sailors to fight with. As Britain—the Allies’ last toehold in Europe—fought for its very life, even a single defeat or succession of defeats such as the Allies had already endured in the Pacific could lead to Pearl Harbor–style attacks on the Australian mainland, or San Francisco and San Diego. The Allies would have no alternative but to sue for peace—not only with the Japanese, but also with the Germans.
The stakes were so high, the secret of JN-25 so important, that people would have given their lives to maintain its secrecy, and eventually would. The alternative in terms of human suffering and wasted lives was simply too appalling to contemplate.
Holmes’s contribution in the example above was like a tiny tessera in the mosaic of intelligence that Rochefort’s group was building, but it was significant nonetheless. When dealing with intelligence, more is always better, and in this case Hypo had discovered that the Japanese were monitoring the weather on Woodlark, an inconspicuous island in a tiny archipelago east of Papua New Guinea. Experience had proven that the advancing Japanese navy had an interest in the weather wherever they were, or would soon be. At about this time, Rochefort’s group had also discovered an increasing number of references to a coded place-name called “MO.” Although encoded—even within superencrypted JN-25—Hypo had noticed patterns between these two-letter designators: They seemed to indicate the first two letters of the place-names, and if such was the case here, MO stood for Port Moresby, a possible invasion site on the southern coast of Papua New Guinea. The Solomon Islands were nearby, and just across the Coral Sea was Australia. If the Allies lost Port Moresby, they would lose all of New Guinea. If the Japanese took the Solomons, they would establish not only a choke hold on Australia, but also a defense against their eastern flank, and multiple staging sites for invasions in any direction.
Working against time, the men of Hypo coasted slowly up and down the cool, clammy halls like wraiths. They had bags under their bloodshot eyes, their expressions crazed with exhaustion and the effects of Benzedrine, an amphetamine that Dyer kept on his desk like breath mints, and that they popped into their mouths every so often like candy to stave off sleep, to postpone eating, to keep their minds on that elusive thread, that hunch, that euphoric state of fixation buzzing about their heads that nagged them even in fitful bouts of sleep on their cots like a gambler’s favorite long shot. The sunless flicker of the fluorescent lights, the sound of shuffling papers and clacking Teletype keys, the smell of stale cigarette smoke and the manila-colored punch cards as they were fanned out and stacked up, comprised a weird amalgamation of human aspiration and the efficiencies and horrors of modern technological war, like a ghost heaving and clattering in the guise of a war machine.
The machina ex deo worked relentlessly to create what would be, for a time, the Japanese fighting man’s worst nightmare. In a mysterious series of events that flowed from bad luck into some accursed fate, it frustrated his every move, turned his food to maggots if he ever got it, denied his comrades bullets and bandages, seeming to turn the sun’s very face away inexorably from him by degrees until he faced starvation, defeat, death, and overwhelming batteries of hostile guns. Ultimately, with nowhere to turn and nothing to lose but his dignity, he would very often face his own rifle barrel.
The intelligence derived from decrypted radio transmissions was so secret that the U.S. government created a new security level beyond top secret to describe it: ULTRA. The British had a more fitting code name, Magic.
For Jasper Holmes, the omniscience would prove a Faustian bargain.