Joseph J. Rochefort, the Priceless Advantage, and Victory at Midway

Joe Rochefort never rose to flag rank, never saw combat, and performed his war-winning work as a commander. A modest man devoted to duty over self, his remarkable achievements were known to but a few. Only after his death did Rochefort receive the attention he deserved. Like so many Sailors engaged in secret work, Joe Rochefort had served in silence. Yet his brilliance, determination, innovation and, above all, his selfless dedication to the U.S. Navy and the nation, remains a benchmark of excellence and a model for his successors.

His early years offered few clues of the greatness to come. Of modest background, Rochefort enlisted in the Naval Reserve Force in 1918, hoping to become an aviator. As he was neither a Naval Academy man nor a college graduate, he stood little chance of earning his wings of gold. Yet he stayed in the U.S. Navy after World War One and was commissioned an ensign after graduation from the Stevens Institute of Technology.

Thus began a conventional line officer’s career, with service in engineering and deck duties in the fleet. And so it might have continued but for a chance observation in 1925 when the junior officer was serving on the battleship Arizona. The executive officer discovered that Rochefort like crossword puzzles – a fact that moved the executive officer to recommend Rochefort to Lieutenant Laurence Safford, then serving in Washington, DC, in a secret job.

Lieutenant Safford was looking for promising naval officers who excelled at crossword puzzles – a sign of aptitude in codebreaking. Safford was the newly appointed head of the euphemistically termed “Research Desk” of the Code and Sign Section located in the Navy Department building on the National Mall in Washington, DC. This fledging outfit – the whole complement could sit at a small table and leave chairs empty – was devoted to studying, and breaking, foreign naval codes. They called themselves cryptologists, what are popularly termed codebreakers, speaking to no one about what they did.

Lieutenant junior grade Rochefort reported for duty in October 1925 and quickly became the shining star of the program, displaying a remarkable aptitude for cryptanalysis, the cracking of codes. He excelled in the unit’s informal training program, and when Safford returned to line duty at sea in 1926 – there was no career path in intelligence, tours with the fleet were necessary to get promoted – Rochefort found himself the head of the Research Desk, which was soon renamed OP-20-G.

In three years, Rochefort honed OP-20-G’s attack on the codes of the main enemy, the Imperial Japanese Navy. Thanks to the theft of a Japanese codebook, Rochefort and his tiny team made significant breakthroughs in exploiting sensitive Japanese naval communications. But heading the team pushed the workaholic Rochefort to the breaking point.

He was sent to Japan in 1929 for a three-year stint to learn the language, a needed rest. Rochefort healed his ulcer and insomnia and acquired excellent Japanese. The tight-lipped officer was a model student. A fellow officer in the program recalled that, in three years together, Rochefort never once mentioned his OP-20-G assignment. On the eve of World War Two, Rochefort was the only officer in the U.S. Navy who was both a cryptanalyst and a Japanese linguist.

In early 1941, with a Pacific War looking increasingly likely, Safford, again the chief of naval cryptology, dispatched now-Commander Rochefort to Hawaii to head up the codebreaking effort against the Japanese navy. Rochefort’s team was known officially as the Combat Intelligence Unit, unofficially as Station HYPO, and he selected the best officers and men he could find to tackle the vexing problem of breaking into the enemy’s fleet ciphers. HYPO’s work was starved of funds – most of OP-20-G’s resources were devoted to the German U-Boat threat in the Atlantic – but as was his custom, the quiet and studious Rochefort drove his Sailors hard and himself harder, according to his command philosophy, prominently displayed above his desk: “We can accomplish anything provided no one cares who gets the credit.”

In what they called “the dungeon,” a dark and windowless room buried in the Pearl Harbor administration building, behind the supply office, to which almost nobody had access, Rochefort’s team put in long hours doing mysterious work. They were striving for breaks in JN-25, which was the primary Japanese naval system, an exceptionally difficult code to exploit. On the eve of the attack on Pearl Harbor, Rochefort’s efforts had begun to pay off – HYPO was breaking into three to four percent of JN-25 traffic – but it was not enough. Shortages of men, funds, and equipment, plus a strong effort against the Japanese Flag Officers’ Code, a rival system, meant that JN-25 was barely being broken.

Rochefort took the December 7 attack hard, swearing to never fail again. There had been no actionable warning. His response was trademark: “I can offer a lot of excuses, but we failed in our job. An intelligence officer has one job, one task, one mission – to tell his commander, his superior, today what the Japanese are going to do tomorrow.” And so he did.

Determined to give the Pacific Fleet’s new commander, Admiral Chester Nimitz, the intelligence he needed to defeat the Japanese, Rochefort descended into HYPO’s dungeon on the morning of the Pearl Harbor attack and hardly left for the next half-year. A demon for work, Rochefort led the all-out assault on JN-25. Finally, he had the resources he needed to get the job done. New equipment appeared. Sailors were no longer in short supply. Rochefort took all the help he could get, even pressing into service the band of the sunken battleship California; the shipless musicians proved to be surprisingly adept codebreakers.

Twenty-hour days became Rochefort’s norm in the winter of 1942. He rarely left his office, even to sleep; he personally translated much of the intercepted traffic. Life in the dank dungeon was difficult, but the cryptologists admired Rochefort for his determination to win. His ardent desire to do the impossible was infectious, and he saved the hardest tasks for himself.

Insanity jokes abounded. Rochefort’s line, “You don’t have to be crazy to work here, but it helps,” became a mantra. The commander was not a stickler for discipline – he was known to wear a smoking jacket in his too-air-conditioned office, which was kept cold to keep the codebreaking machines from overheating – but he cared a great deal about performance. His performance concern was particularly apparent beginning in the third week of March 1942. HYPO had finally won the battle with JN-25, and Rochefort’s team commenced “current decryption”: they were reading secret Japanese fleet communications nearly as fast as the intended recipients were.

Importantly, Rochefort had developed a seamless partnership with Commander Edwin Layton, an old friend and Nimitz’s intelligence officer. Together, they assembled a detailed picture of the Japanese fleet and its operations that wasn’t encouraging. The Japanese had more – and in most categories better – ships and aircraft, plus they held the strategic advantage. Admiral Nimitz faced ominous choices; one significant misstep could cost the U.S. Navy what had not been sunk at Pearl Harbor.

The only advantage the Pacific Fleet held over the enemy was in intelligence – an advantage that was later termed “priceless” by Nimitz. By the spring, thanks to Rochefort’s efforts, which were providing an average of 140 decrypted JN-25 messages each day, it was evident that the Japanese were planning a major naval offensive soon. But where?

Rochefort confidently predicted an enemy drive across the central Pacific, aimed at Hawaii via Midway Island. Others, including Nimitz’s staff and OP-20-G headquarters in Washington, disagreed, believing the offensive was directed at the Aleutians. To prove his point, Rochefort devised a clever deception operation using faked U.S. Navy traffic which convinced Layton and Nimitz that Midway was indeed the enemy’s target. This gamble led directly to the Battle of Midway, the incredible victory of June 4-6, 1942, the greatest triumph in the history of the U.S. Navy, and thereby turned the tide in the war with Japan. Had it not been for Rochefort, Nimitz’s outnumbered carriers would have been in the wrong place, two thousand miles to the north off Alaska, when Admiral Nagumo’s fleet appeared off Midway. The courage and skill of America’s Sailors, particularly of naval aircrews, won the battle, but Rochefort’s codebreaking triumph made the victory possible.

His rewards for this epic feat were few. Higher-ranking rivals in Washington, who had embarrassingly bet against Rochefort’s Midway gamble, exacted their revenge. Over Nimitz’s objection, Rochefort was recalled to the Pentagon and forbidden to take the ship command he wanted – he knew far too many secrets to be allowed to go to sea – and instead he wound up commanding a dry dock. Rochefort never received a decoration for his war-winning work and never worked on codes again. He peacefully remained silent about his war service.

Only after Rochefort’s death in 1976, as World War Two codebreaking secrets were declassified, did the public learn the remarkable story of Station HYPO and how it made victory at Midway possible. Finally, a decade after his death, Joe Rochefort’s family received the President’s National Defense Service Medal, the highest military award during peacetime, from President Ronald Reagan, for his support to the Battle of Midway. As long as there are cryptologists in the U.S. Navy, the name Joe Rochefort will be spoken with reverence.

Note: an earlier version of this article appeared in Leadership Embodied: The Secrets to Success of the Most Effective Navy and Marine Corps Leaders, published by the Naval Institute Press in 2005. In the 2019 film Midway, which on the whole is quite historically accurate, the role of Commander Rochefort (played by Brennan Brown) in the story is conveyed more or less as it happened.