Spies, Ciphers, and Guerrillas, 1939 - 1945 (2016)
Japan's diplomatic code ("Purple") had been broken by US codebreakers in August 1940, and in the months before Pearl Harbor, the U.S. military/gov't had as much information beforehand as did Stalin before Barbarossa. The U.S. response to all that intelligence was just as moronic as Stalin's; similar to the British experience, it was only after being dragged into war that the U.S. intelligence apparatus developed into being seen as an asset. But in the months before Pearl, neither Army or Navy intelligence did much of anything to learn more about the Axis, especially Japan.
However, in June 1942, a huge break in the Pacific for the U.S. occurred that would change the course of the war against Japan, all within 48 hours. It was the largest single intelligence coup of World War II; the U.S. Navy officer that led the charge in terms of that intelligence was Lt. Cmdr Joseph Rochefort. Rochefort, lost in history, and whose skill set flew below the radar in the Navy, was the right man in the right spot at the right time for his nation.
By 1927, Rochefort had enough of Navy politics, and Lt. Rochefort became an executive officer (XO) on a destroyer. Rochefort's personality wasn't a good fit in the closed world of a warship; for example. he told his captain that trivial communications didn't need to be encoded, and that suggestion wasn't received warmly, to say the least. In 1929 Rochefort was posted to Japan in order to learn Japanese, and he remained there for three years. Rochefort was so introverted that he never mentioned to his superiors that he was interested in codebreaking, so he spent the 1930s at sea as a gunnery officer, then intelligence, and lastly navigation.
In October 1939, Rochefort was posted in Pearl Harbor, and he quickly became appalled at the casual routines on station, but he shared the belief with everyone else at Pearl that the they had nothing to fear from Japan. That same year, General George C. Marshall (the top ranked general in the U.S. Army, based in Washington, D.C.) relaxed the strict interpretation of U.S. neutrality towards Japan in terms of intercepting wireless traffic, which made codebreaking possible, starting with "Purple".
Rochefort was asked to lead a group of cryptanalysts at Pearl (COM 14, "Station Hypo") by a superior officer that had worked with Rochefort and appreciated his interest/abilities. At age 41, Rochefort accepted the post somewhat reluctantly, dreading the politics involved. In June 1941, Rochefort took up additional responsibilities and reported directly to Admiral Husband Kimmel, the Pacific Fleet Commander-in-Chief. Rochefort was promoted to Lieutenant Commander in October 1941; little did Rochefort know that inside of a year, he and his team would make history in the basement ("The Dungeon") of the Navy Yard administration building.
COM 14 received zero respect from the Navy, since they hadn't yet produced anything of value, and were never in harm's way. Just as with Bletchley, only those that worked at breaking codes knew what they could achieve, and what that would mean to the U.S. war effort. COM 14 was not apprised of successes in other departments, such as the Army breaking "Purple", and "Orange" being "pinched" (taken without being noticed) from a Japanese freighter in San Francisco. COM 14 didn't even know what U.S. Fleet Intelligence was up to, and they were located just one mile away from COM 14 in Pearl Harbor.
By December 1941 COM 14 hadn't come close to breaking the Japanese Flag Officer's Code in large part because there was too little traffic to intercept/analyze. COM 14 knew that Japan was planning something big, but Rochefort et al had no idea what that could be. In mid-November 1941, COM 14 had lost track of 6 Japanese aircraft carriers due to Admiral Yamamoto's radio smokescreen. On 29 November 1941, Rochefort dispatched four members of COM 14 to listening posts, looking for a "Winds" message, which in essence meant that an attack was coming.
On 30 November 1941, Japan, for the second time that month, changed all of the call signs for their warships, yet another indication that an attack was imminent. On 3 December 1941, Washington, D.C. informed the command at Pearl Harbor, as well as COM 14, that Japan had ordered their diplomatic branch to destroy their codes and ciphers; the Japanese Consul in Honolulu was also ordered to do so by Tokyo.
After Pearl Harbor, the main question was how to strike back against Japan. Admiral Chester Nimitz, the new Pacific Fleet Commander, blamed Navy intelligence, especially COM 14, for the lack of preparation before Pearl Harbor, and Rochefort was told by a friendly officer that the Navy Department also shared Nimitz's belief. COM 14's challenge was to break Japan's new JN-25b Fleet Code. Rochefort's stock with Nimitz stayed low until COM 14 told Nimitz that Japan was heading for Rabaul. Then COM 14 highlighted Japan's weaknesses and strengths in the Marshalls and the Gilberts, which led to successful attacks by Navy task forces commanded by Halsey and Fletcher, respectively.
On 2 March 1942, Rochefort and COM 14 correctly predicted a Japanese air raid on Hawaii, which occurred on 4 March 1942; it wasn't much of a raid, but COM 14 again was correct. During March 1942, Rochefort predicted an air raid on Midway, and it was during his analysis of the Japanese code JN-25b that he discovered that the ID for Midway was "AF". By then, COM 14 was intercepting/analyzing more-and-more JN-25b traffic, and by early-May 1942, Rochefort told Nimitz that Japan was again planning something very big, but he wasn't sure where, when, or with what.
Rochefort, on 9 May 1942, told Nimitz that Japan would set sail for a major operation on 21 May, but the destination remained unknown . . . was it to be Pearl again, the West Coast, or the Aleutian Islands. On 13 May 1942, COM 14 decryptions revealed that
Yamamoto wasn't going to Pearl or the Aleutians in force, but to Midway Island; Rochefort, with his giant brain, remembered from March 1942 that "AF" ("Affirm Fox") was the Japanese code name for Midway. After a presentation to Nimitz's second-in-command at COM 14, Nimitz (after being briefed) was convinced that Midway was the target, and that Japan was going to commit four large aircraft carriers to the attack.
On 16 May 1942, Nimitz went all-in on COM 14's intelligence on Midway, and an important intercept later that day confirmed the fly-off positions from the Japanese carriers. Nimitz was the only one in the Navy, or in Washington, D.C., that believed Rochefort and COM 14, and Rochefort wanted to show the powerful naysayers that Midway was the target. The result, on 19 May 1942, was the "water message"; Rochefort, via an uncoded message, sent out false information that Midway was short of fresh water. Very soon after the message was sent, Japan sent out a coded message that "AF" was short of fresh water, and Midway was confirmed as the target. Nimitz himself engaged in deception staging a token air raid on Tulagi
which convinced Tokyo that the U.S. aircraft carriers where nowhere near Midway.
The Navy did its absolute best to ruin the surprise Nimitz had in store for Japan at Midway via senseless radio traffic that should have alerted Yamamoto that the U.S. was lying in wait. But Yamamoto dismissed the radio traffic as unimportant, so he didn't lift his order of radio silence to inform Admiral Nagumo of what had been intercepted.
Midway was foremost a victory for intelligence; Nimitz publicly stated that Rochefort deserved credit for Midway, but those words were his only tangible reward. Rochefort was denied a Distinguished Service Medal by the Navy because he wasn't involved in combat. Rochefort's next (and last) accomplishment in intelligence occurred when he predicted that Japan would land on
Guadalcanal on 5 July 1942.
Sadly, the Navy and D.C. never viewed Rochefort as a hero, but as an insubordinate cuss, and on 14 October 1942, he was relieved of his command at COM 14 and was assigned to be in command of a floating dry dock in San Francisco. The U.S. Navy's treatment of Rochefort was about as cold-blooded as it could get in terms of a bureaucracy/hierarchy dealing with a hero that changed the course of the War in the Pacific for his nation. Eventually, in 1944, Rochefort was placed in charge of the Pacific Strategic Intelligence Unit.
Rochefort died in 1976, undecorated and obscure; he was posthumously given the Distinguished Service Medal in 1985. Rochefort deserves his place in U.S. History that was denied him by the absolutely malicious and/or incompetent figures in positions of power in the United States Navy and the federal government in Washington, D.C. during the War in the Pacific.
Japan's initial war strategy in the Pacific?