Joseph Rochefort: Wikis


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Joseph John Rochefort
1898 – 1976 (aged 77–78)
Joseph rochefort.jpg
Joseph J. Rochefort
Allegiance United States of America
Service/branch United States Navy
Years of service 1918-1947, 1950-1953
Rank Captain
Commands held Station Hypo
Battles/wars World War II
Korean War
Awards Distinguished Service Medal
Presidential Medal of Freedom

Captain Joseph John Rochefort (1898–1976) was an American Naval officer and cryptanalyst. His contributions and those of his team were pivotal to victory in the Pacific War.

Rochefort was a major figure in the United States Navy's cryptographic and intelligence operations from 1925 to 1946, particularly in the Battle of Midway, which his skills and effort helped win. Fluent in Japanese, he headed the Navy's fledgling cryptanalytic organization in the 1920s and provided cryptographic support to the U.S. Fleet. At the end of his naval career (1942–1946), Rochefort successfully headed the Pacific Strategic Intelligence Group in Washington.


Early career

Rochefort enlisted in the Navy in 1918. He was commissioned as an ensign after graduation from the Stevens Institute of Technology. Rochefort's tours ashore included cryptanalytic training under both Captain Laurance Safford and the master codebreaker, Agnes Meyer Driscoll, in 1925; a stint as second chief of the Division of Naval Communications' newly created cryptanalytic organization, OP-20-G, from 1926 to 1929; training in the Japanese language from 1929 to 1932; and a two-year intelligence assignment in the Eleventh Naval District, San Diego, from 1936 to 1938. Until 1941, Rochefort spent nine years in cryptologic or intelligence-related assignments and fourteen years at sea with the U.S. Fleet in positions of increasing responsibility.

World War II


Pearl Harbor

In early 1941, Laurance Safford, again chief of OP-20-G in Washington, sent Rochefort to Hawaii to become Officer in Charge (OIC) of Station Hypo in Pearl Harbor. The reasons for Rochefort's appointment were obvious: he was an expert Japanese linguist, an experienced and very talented intelligence analyst, and a trained cryptanalyst. He by this time thoroughly understood the capabilities, and the limits, of radio interception of communications of enemy forces and what could be done with this information.

Rochefort handpicked many of HYPO's staff, and by the time of Pearl Harbor, had gotten many of the Navy's best cryptanalysts, traffic analysts, and linguists, including Thomas Dyer, Wesley A. (Ham) Wright, Joseph Finnegan, General Alva Lasswell, Thomas Huckins, and Jack Williams.

Rochefort had a close working relationship and friendship with Edwin T. Layton (later Rear Admiral Layton), whom he first met on the voyage to Tokyo to learn Japanese, which Layton was also undertaking at the Navy's request. Layton was in 1941 the chief intelligence officer for Admiral Husband E. Kimmel, Commander of the Pacific Fleet. According to Layton's book, And I Was There: Pearl Harbor and Midway – Breaking the Secrets (1985), both he and Rochefort were denied access to decrypts of diplomatic messages sent in Purple, the highest level diplomatic cypher, in the months before the Japanese attack. This was the result of a monopoly on intelligence achieved by the Director of the War Plans Division, Richmond K. Turner in Navy headquarters in Washington.[1]

Rochefort and Layton, and their commander, Admiral Kimmel, were kept in the dark.[2] They were aware that negotiations with the Japanese were breaking down, and they had even been issued a general "war warning" by Washington on 27 November, but they could not distinguish between deterioration and imminent threat, nor had they any reason to suspect an attack 4000 miles east of the Philippines, where Douglas MacArthur and the US Asiatic Fleet were stationed. More importantly, they were in the dark about the fact that the spy whom Japan had sent to Honolulu, Takeo Yoshikawa, was sending daily reports – via the diplomatic messaging – on the precise locations of ships in Pearl Harbor, using a grid system clearly meant as a precise aid to attacks by submarines and bombers (unlike other port and harbor information being transmitted to Tokyo from other parts of the world).[3]

Battle of Midway

After the Japanese attack, Navy cryptographers increased their attempts to break into the highest-level JN-25 Japanese Navy encrypted communications. Station CAST (Cavite in the Philippines), Station HYPO (at Pearl Harbor; "H" for Hawaii), OP-20-G in Washington (NEGAT, "N" for Navy Department), with assistance from both British cryptographers at the Far East Combined Bureau (in Hong Kong, later Singapore, later Ceylon), and Dutch cryptographers (in the Dutch East Indies), combined to break enough JN-25 traffic to provide useful intelligence reports and assessments regarding Japanese force disposition and intentions in early 1942.

How much of this work was done by Station HYPO is still controversial, but it is clear that Station HYPO made major, and likely the most critical, contributions.

Station HYPO (in effect Rochefort) maintained that the coming Japanese attack would be in the Central Pacific, while OP-20-G (with support from Station CAST) insisted it would be elsewhere in the Pacific, probably the Aleutian Islands.[4] possibly Port Moresby in Papua New Guinea, or possibly even the west coast of the United States. (See Layton, p. 421). OP-20-G, which had been restructured (Safford having been reassigned), under the command of officers not trained as cryptanalysts, also insisted that the attack was scheduled for mid-June, not late May or early June, as Rochefort maintained. Nimitz's superior in Washington, Admiral Ernest King, was being advised by OP-20-G.

What was clear was that there was an "invasion force" associated with target site “AF”, but where or what was AF was the subject of debate.

One of the Station HYPO staff, Jasper Holmes (see Layton, p. 421), had previous experience with Midway; as an engineer, he had studied the Pan Am facility there. He had the idea of faking a water supply failure on Midway Island. He suggested using a cleartext emergency warning, provoking Japanese JN-25 traffic on the subject, thus testing whether Midway was a target or not. Rochefort took the idea to Layton, who took it to Admiral Nimitz (who had replaced Kimmel), and Nimitz approved it.

The Japanese took the bait. They broadcast instructions for the code group for the major attack point to load additional water desalination equipment, thus confirming Rochefort’s analysis.[5] Layton notes that the instructions also “produced an unexpected bonus”. They revealed that the assault was to come before mid-June.

Washington still was not convinced, however.[6] Actually, the disagreement with Washington as to the date of the attack stimulated Rochefort’s team to one of their finest efforts. Layton refers to the date-time data in Japanese naval messages as being “superenciphered,” meaning that this data was encoded even before it was added to the JN-25 cipher. When HYPO made their all-out effort to crack this and prove Washington wrong, they started by searching the stacks of printouts and punch cards for five-digit number sequences. Those they found were in low grade codes, a poor starting point, but a starting point.

Layton, pp. 427–8, goes on to say the next task was to unravel the cipher itself. He credits Lieutenant Joseph Finnegan, a linguist-cryptanalyst, as the person who "finally hit upon the method that the Japanese had used to lock up their date-time groups." The method involved what he calls a 12 x 31 "garble check" --12 rows for months, 31 columns for day.

The 31 kana [Japanese syllabic scripts] of the first row were A, I, U, E, O, KA, KI …………… HA, HI, HU, HE, HO. The second row was I, U, E, O …………… HE, HO, A; the third, U, E, O ……… HO, A, I, and so on, for 12 rows. At the left, representing the 12 months, was a column of 12 kana, different from those in the table – SA, AI, SU, SE, SO, TA, TI, TU, TE, TO, NA, NI (SA for January, NI for December).

Thus: "To encipher, for example 27 May, one picked the 5th line (May=SO), ran across to the twenty-seventh column, HA, and recorded the kana at that intersection, HO. The encipherment, then, was SO, HA, HO, the third kana providing the garble check."

An intercept of 26 May with orders for two destroyer groups escorting invasion transports was analyzed with this table and “really clinched the pivotal date of the operation” as either 4 or 5 June.

During May 1942, Rochefort and his group decrypted, translated, reviewed, analyzed, and reported as many as 140 messages per day. During the week before Nimitz issued his final orders, “decrypts were being processed at the rate of five hundred to a thousand a day.”

Just processing the intercepts was a demanding physical effort, because each one had its five-digit group punched into IBM cards. A single message might require anywhere from sixty to seventy of the slim, manila three-by-seven, eighty-column IBM cards. A lengthy signal could easily consume two hundred of them. Each one had to be hand-punched and sorted by the former band members of battleship California sunk on the Day of Infamy, who manned the IBM machines that they kept chattering around the clock.[7]

Layton goes on to describe how:

Hypo was consuming nearly three million punch cards a month. Just keeping Hypo supplied without arousing the suspicion of outsiders created a security risk. And storing all the cards in hundreds of open boxes for future reference created severe problems. For the printouts produced from the tabulating process, from which Japanese messages could be translated, were piled up on desks, floors, and every available space.

There are stories about Rochefort, in his bathrobe, working 36 hour continuous shifts in Station HYPO's basement offices. Rochefort, in his oral history interview referenced below, says,

I started to wear a smoking jacket over the uniform and I wore this darn thing because it had pockets in it and I could get my pipe and my pouch this way. Then my feet got sore. It was from the concrete floor we had down there. That's all we had – a concrete floor. And my feet kept getting sore. So I started wearing slippers because the shoes hurt my feet.

Layton also describes how, in the critical weeks of May, Rochefort installed a cot so that he could be on call at all times. Other team members also put in long hours, fighting fatigue “with Benzedrine tablets that were passed around like jellybeans,” according to Layton.

All this effort and talent, and all these ideas, enabled Admiral Nimitz to set up the ambush which led to victory in what was the turning point of the Pacific War, the Battle of Midway.

In the movie Midway, then-Commander Rochefort was portrayed by Hal Holbrook.

After Midway

“The denouement of the Battle of Midway was not one of the U.S. Navy's finest hours.”[8] So opens the discussion by Steven Budiansky of the Navy's treatment of Rochefort after Midway.

When Nimitz forwarded to Admiral King the recommendation of Fourteenth Naval District command that Rochefort be awarded the Distinguished Service Medal, Rochefort, "with a keener measure of Washington politics than his commander", said that it would only "make trouble."

He was right. Redman was continuing his campaign to centralize control of all radio intelligence work under OP-20-G in Washington and Rochefort was continuing to resist; it was quickly degenerating into a fight over who deserved credit for breaking JN-25 and correctly anticipating the Japanese plans for Midway. The honors for breaking JN-25 were properly shared. Of the 110 vital messages broken in advance of Midway, 49 were read simultaneously by both stations, 26 by Hypo only, and 35 by Washington only. But when it came to drawing the correct conclusions from those messages, Hypo won hands down. Had Nimitz been swayed by Washington's analysis, the Japanese ambush would very likely have succeeded.

But Washington, in effect the Redman brothers (John and Joseph), were now “claiming sole credit for the victory at Midway”, and arguing that units in combat areas could not be relied upon to do more that simply read enemy messages and perform “routine work necessary to keep abreast of minor changes in the cryptographic systems involved." The older brother, Captain Joseph R. Redman, now Director of Naval Communications, made the preposterous argument that Rochefort was merely an “ex-Japanese language student" who was "not technically trained in Naval Communications."

These assertions were accepted by Admiral King’s chief of staff, and King denied Rochefort his medal.

Budiansky continues:

A year later, Commander Jack S. Holtwick, who had run the IBM machines at Station Hypo, called on Joseph Redman, now a rear admiral. In the course of conversation Redman casually remarked that Station Hypo had "missed the boat at the Battle of Midway," but Washington had saved the day. The lie took Holtwick's breath away – especially since Redman had to know that Holtwick knew the opposite was true. That was the first real inkling the Hypo crew had of how completely Washington had stolen credit for the victory at Midway. Shortly before his death in 1985, Dyer wrote: "I have given a great deal of thought to the Rochefort affair, and I have been unwillingly forced to the conclusion that Rochefort committed one unforgivable sin. To certain individuals of small mind and overweening ambition, there is no greater insult than to be proved wrong." Two of the Station Hypo team, Dyer and Holmes, finally did receive the Distinguished Service Medal after the war. Rochefort finally did, too – in 1985, nine years after his death.

As Budiansky and others have noted, the argument in favor of centralization was not without merit. The labor and resources involved in breaking codes, as the quotations from Layton about IBM punch cards and printouts demonstrate, was great, and it was necessary to avoid duplication of effort. There was also a need to ensure that all relevant intelligence data bearing on an issue was viewed and analyzed.

But centralization became a convenient club to beat Rochefort with, and the Redman brothers beat away unmercifully. Finally on September 15, Rochefort, with Nimitz's approval, sent a blistering memo insisting that he in effect was answerable only to Nimitz, and Washington should butt out. Payback came on October 22, 1942: Rochefort was summoned to the Navy Department for "temporary additional duty." When Nimitz protested, he was assured that Washington simply needed Rochefort's expert advice. Rochefort once again read the situation more accurately than his boss; he told everyone that he was not going to be coming back.

Rochefort was right.

Rochefort, meanwhile, proceeded to make "several mistakes in a great big hurry," as he himself put it. Worn out, suffering from bronchitis, and made more prickly than ever by the Redmans' attempt to steal the credit for his work, Rochefort said he would not accept any assignment in radio intelligence unless he was sent back to Honolulu as officer in charge. Failing that, he demanded combat duty. Cryptanalysts were forbidden to enter combat zones: they knew too much that they might give away if captured and tortured by the enemy. But Rochefort pulled every string he could think of and was offered command of a destroyer, only to turn it down because the ship was leaving at once from San Francisco and he had promised his wife they would visit their son at West Point that same weekend – "a very stupid thing for me to have done," Rochefort later said. He ended up in command of a floating dry dock in San Francisco. He never worked on codes again.


Navy Distinguished Service Medal
The Presidential Medal of Freedom

Rochefort died in 1976. In 1985, he was posthumously awarded the Navy Distinguished Service Medal. In 1986, he posthumously received the Presidential Medal of Freedom, the highest military award during peacetime, for his cryptographic work in the period before the Battle of Midway. In 2000, he was inducted into the National Security Agency, Central Security Service Hall of Fame.


  1. ^ Layton, Admiral Edwin T., USN, Ret., with Pineau, Roger, Captain USNR, Ret., and Costello, John, And I Was There: Pearl Harbor and Midway - Breaking the Secrets, William Morrow and Company, Inc., New York, 1985, ISBN 0-688-04883-8, p. 115
  2. ^ Layton, Pineau, and Costello, And I Was There: Pearl Harbor and Midway - Breaking the Secrets, pp. 21-22
  3. ^ Layton, Pineau, and Costello, And I Was There: Pearl Harbor and Midway - Breaking the Secrets, pp. 162-163
  4. ^ Lundstrom, First South Pacific Campaign, p. 155
  5. ^ Cressman et al., A Glorious Page in Our History, p. 34
  6. ^ Layton, Pineau, and Costello, And I Was There: Pearl Harbor and Midway - Breaking the Secrets, p. 421
  7. ^ Layton, p. 422
  8. ^ Budiansky, Stephen. "Denouement: 'Radio Intelligence' Vindicated".  


This article is derived, in part, from the public domain NSA online biography.

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