The Codebreakers Who Won the Battle of Midway

today we're diving into the Battle of Midway a turning point of World War II but our story isn't merely about military strategy and brutal combat it's about the shadow war of code breaking the cryptologists the unsung heroes armed with knowledge and intuition played an essential role in securing Victory so join us as we journey back to 1942 through the murky depths of deception and intelligence to uncover how the Battle of Midway Was Won not just on the Seas and in the skies but also within the cryptic world of coded messages as the mighty aircraft carrier Fleet of the Japanese Navy Advance towards Midway atoll on the morning of June 4th 1942 they were unknowingly heading into a trap laid by three U.S Navy carriers this strategic placement of the American Fleet wasn't coincidental as the U.S Navy's code Breakers had successfully intercepted and deciphered Japanese radio signals thereby allowing Pacific Fleet Commander Chester Nimitz to catch the Japanese by surprise at Midway this intelligence coup is now widely recognized despite the secrecy around U.S Communications intelligence during World War II the role of code Breakers in revealing Japanese plans for Midway was first alluded to by journalist Stanley Johnston in a newspaper article published shortly after the battle although thousands of military and civilian Personnel were involved in the American radio intelligence effort by the end of the war it was a select few who managed to accomplish the Herculean task of manually cracking the enemy's coded messages it's worth noting that despite the existence of decoding machines during the war most of the critical code breaking work in the early months of 1942 was done by hand the Imperial Japanese Navy during the Pacific War relied heavily on manual book-based codes for their operational Communications while Japanese diplomats made use of a machine-derived code the infamous purple machines the Navy having thousands of units sending radio messages leaned towards their manual coding system these Naval radio messages from the Japanese were sent in a tweaked version of Morse code messages intercepted by the Allies were logged as a sequence of numbers which were then decoded by the code Breakers to form words and phrases no machine was capable of this task though rudimentary tabulating equipment might Aid in identifying patterns amidst the seemingly random digits it was down to individual cryptanalysts to ascertain the meaning of each ciphered word to do so they exhaustively analyzed thousands of messages identified recurring number sequences and recognized patterns leveraging their understanding of Japanese Naval protocols strategy and the language itself these code Breakers made well-informed deductions the code breaking process demanded a high degree of focus and Immaculate attention to minuscule details and the skill to discern nearly imperceptible patterns as per historian David Khan in his 1996 book The Code Breakers this work was described as the most excruciating exasperating agonizing mental process known to man advancements in code breaking were slow and gradual every small Triumph in deciphering a code group the cluster of numbers that stood for words or phrases was meticulously noted and communicated to other cryptanalysts as they grappled with interpreting other messages this was a slow and laborious process it was not a dramatic scene where a sudden spark of insight would expose the concealed secrets of a specific message instead the everyday reality of kryptonalyst was often marked by frustration and a pervasive sense of defeat however the effort was not in vain the victories of the U.S Navy at the Coral Sea and Midway in early 1942 who came at a time when the Imperial Japanese Navy had a clear advantage over the U.S Pacific Fleet in terms of the number of ships training tactics and battle experience these victories were made possible due to the intelligence gathered from American radio communications which included code breaking traffic analysis Direction finding and intelligence analysis despite starting as a typically understaffed ill-equipped underfunded and undervalued operation the U.S Navy's pre-war radio intelligence effort amazingly transformed into an organization capable of altering the course of the Pacific War this Evolution could be seen as nothing short of miraculous the United States was among several Nations that carried out Communications intelligence operations during World War One the first war where radio technology was extensively employed prior to the war there was no American organization capable of intercepting the radio signals of other nations however in 1917 when the U.S joined the conflict the U.S army set up the nation's first code breaking office the Navy on the other hand relied on the code breaking support of the British royal Navy and did not immediately create a similar office yet during the war's final days the Navy allocated one hundred thousand dollars to a clandestine Office of Naval intelligence or Oni account to finance future code breaking Endeavors surprisingly it was neither the Navy nor the army that achieved the first significant code breaking victory for America it was the U.S Cipher Bureau formed in 1919 by the state and War departments and efficiently led by cryptologist Herbert o Yardley after a year of effort the bureau cracked Japan's primary diplomatic code affording the U.S a significant Edge during the naval disarmament talks from 1921 to 1922 even though the Navy reaped considerable benefits from the bureau's Triumph it didn't rush to cultivate its own code breaking skills especially when there were faster methods to infiltrate in enemy's Communications by 1920 the secret Oni fund had financed a series of break-ins at the Japanese consulate in New York City then in 1923 a similar operation yielded a major code breaking breakthrough when navy agents successfully pilfered a Japanese code book from the luggage of a visiting naval officer in response the Navy set up a modest code breaking section to exploit this opportunity and launch further assaults on foreign codes and ciphers from this somewhat dubious origin the Navy's code breaking capability began to expand gradually during the 1920s and 30s many individuals who would later play a pivotal role in the Branch's wartime operations began their careers among them were the resilient Agnes Meyer Driscoll who tutored most of the Navy's key wartime cryptanalysts During the interwar period and the astute Joseph J rochfort who would lead the unit that revealed the Japanese plans at Midway during this time under the stewardship of Lawrence F Safford and rochefort the Navy established a network of radio intercept stations developed techniques for deciphering intercepted messages and assembled a small team of skilled cryptanalists and linguists budgetary constraints during the Depression era and the fact that intercepting another nation's radio communications was actually illegal during these years limited the Navy's efforts despite these obstacles by the mid-1930s the Navy had set up the most extensive cryptological division within the American Military under the leadership of Safford and rochefort the Navy established a tripartite cryptological program consisting of Direction finding traffic analysis and crypt analysis or code breaking the program was overseen from the Navy headquarters in Washington DC and included radio intelligence stations at Pearl Harbor in the Philippines promising young officers were dispatched to Japan for three-year stints to acquire Japanese language proficiency understand local customs and familiarize themselves with the culture this knowledge would later be crucial as these officers attempted to infer Japanese intentions from the piecemeal information gathered through radio intelligence given that cryptanalysis was not seen as a path to career advancement the Navy faced challenges in attracting and retaining talented officers in the field for instance despite roachford spending most of the 1930s mastering Japanese and honing his cryptanalysis skills thereby making him arguably the most qualified cryptanalyst in the U.S military the Navy ensured he maintained a well-rounded officer profile by intermittently pulling him away from Communications intelligence work for sea duty this approach was typical for other cryptanalysts as well however during the 1920s and 1930s the Navy successfully laid the groundwork for an exceptionally triumphant and significantly expanded Communications intelligence operation during the Pacific War this growth started in Earnest in the late 1930s as the likelihood of war with Japan increased and picked up pace after the German invasion of Poland in 1939. by the time of the attack on Pearl Harbor the Navy's Communications intelligence structure in the Pacific included listening stations in Guam the Philippines Oahu and Washington State a network of high frequency Direction finding stations scattered throughout the region was also set up along with radio intelligence centers at Pearl Harbor and Cavite in the Philippines another radio Intelligence Center in Washington D.C coordinated radio intelligence activities in the Pacific the Americans also shared information with a British radio intelligence group based in Singapore during this time the three stations cavity Pearl Harbor and Washington DC operated in harmony later on personality disputes and power struggles within the Navy would disrupt this cooperation leading to roachford spending a year in command of a mobile floating Dry Dock however in the months between Pearl Harbor and Midway the collaboration was highly effective by the close of 1941 the Cavite unit situated in Manila had nearly 70 officers and Personnel at Pearl Harbor rochefort was in charge of an organization that consisted of 100 officers and enlisted men the majority were allocated to Direction finding and traffic analysis roles leaving only a few available for code breaking work as the United States and Japan were inching towards war in 1940 and 1941 the Navy primarily depended on radio Direction finding and traffic analysis to keep tabs on Japan's War Readiness traffic analysis was the heart of radio intelligence it focused on gleaning as much information as possible from an intercepted message without actually deciphering it analysts scrutinized details like sender and receiver identities the quantity of radioactivity relationships between senders and receivers traffic patterns that resembled previous operations types of units receiving messages and more through this significant insights about an adversary's operations could be unveiled highly sensitive Direction finding DF antennas spread across the Pacific could pick up radio signals from great distances and pinpoint the exact direction of the radio transmitter if a signal was intercepted by two or more DF locations technicians could map the bearings from these sites and precisely identify identify the transmitter's location while traffic analysis and Direction finding were invaluable they couldn't compete with the rich insights promised by code breaking which had the potential to expose much more about Japanese operations and plans owing to the successful theft of a Japanese code book in 1923 the Navy had made significant Headway against the Japanese red code by the mid-1930s the code being thus named due to the stolen code book copies being bound and read by the Navy when the Japanese replaced the red code with a similar Cipher the blue code the Americans applied their understanding of the former to crack the blue code by 1939 the U.S had broken the blue code and a few minor codes used for weather reports shipping details and Harbor Master operations in late 1940 a joint effort by U.S Navy and army code Breakers also managed to decode the main Japanese diplomatic code unlike the manual red and blue codes this diplomatic code known as Purple was a machine code messages composed of code groups were further encrypted by an electromechanical coding machine impressively American cryptanalysts despite never having seen the original machine managed to decipher the operation of the coding machine through mathematical analysis of intercepted messages they even constructed a functional replica of the device that could remove the encryption of the code groups once the encryption was stripped off the Americans could manually tackle the code groups using conventional cryptanalysis methods so what were the mechanics of manual code breaking how did teamwork pattern identification record maintenance the iterative process of trial and error and Relentless determination culminate in the victory at Midway starting from June 1939 Japan began utilizing a new Naval operations code which the Americans referred to as jn25 although rooted in the preceding red and blue codes jn25 was notably more intricate offering three separate layers of security firstly every word or number in the message was substituted with a five-digit number known as a code group the code comprised over 33 000 unique code groups each signifying a word phrase letter or number this was a step up from previous codes which utilized four character code groups secondly the code groups underwent further encryption or super encryption by appending random numbers to each group these numbers were termed additives and there was a separate book providing thirty thousand of them the additive values were summed with the code groups altering the numbers and concealing the underlying code groups the person drafting the message would randomly choose a starting point in the additive book and then sequentially use the additives each code group was paired with a distinct additive value finally the message Incorporated the initial point in the additive book from where the sequence of additives started this allowed the message recipient to locate the chain of additives the recipient of the message subtracted the additives to expose the underlying code groups and then reference the code groups in the code book to decode the message content the assignment for the Navy's radio intelligence team was multifaceted they had to intercept the message convert the morse code into numbers remove the additives to reveal the code groups and determine the meaning of the code groups this operation was carried out in an assembly line manner with intercepted messages being cataloged assessed scrutinized and decoded successively By Radio men at The Intercept stations and DF sites and cryptanalysts translators linguists data processing assistance and intelligence analysts at the radio intelligence centers intercepted messages were initially scrutinized for information that could be employed in traffic analysis which included the sender of the message recipients call signs used message length time of transmission circuit used message format radio Direction finding data and other external indicators after traffic analysis the intercepts were categorized duplicated and handed over to cryptanalysts these cryptanalysts were then tasked with the seemingly insurmountable job of recognizing the additives stripping them to expose the code groups and decrypting the underlying code groups the intricacies of America's code breaking efforts were shrouded in secrecy for decades following the war as a result there are scant published accounts discussing the steps Krypt analysts took to decipher the additives and code groups The Limited accounts that do exist have cryptanalysts wrestling with how to describe the process although they unanimously concur that it was a taxing Endeavor rochefort recounted starting with what he referred to as the staring process you survey all the messages at your disposal he stated you align them in different ways you jot them down one after the other you transcribe them in varied formats and scrutinize them gradually you'd observe a pattern a distinct correlation would emerge between these messages that's your initial lead some cryptanalysts would disclose additives by hypothesizing potential additives and subtracting them from a column of encrypted numbers extracted from messages if the results were divisible by three a check instituted by the Japanese to prevent coding or transmission errors the code breaker could confirm that they had identified an additive cryptanalysts would assemble new messages on large sheets populated with numbers taken from previous messages to search for patterns if they identified a recurring sequence they would retrieve the earlier messages and scrutinize them for clues that could assist in deciphering the new message at times code Breakers would make informed speculations about the meanings of words or phrases and substitute code groups with those conjectures a technique known as cribbing access to a searchable database of thousands of previous messages was crucial to the code breaking process this was augmented by meticulous creation of charts graphs and tables to spot recurring sequences or patterns nevertheless it often boiled down to an unexpected moment of realization when the code breaker suddenly discerned what they had been seeking this Eureka moment usually meant that a single additive or if additives were already stripped a single code group had been identified considering there were more than thirty thousand additives and over 33 000 code groups deciphering a single word typically marked a tiny advancement moreover the Japanese occasionally updated their code groups and additive books resetting American code Breakers to the starting point despite these hurdles American cryptanalysts persisted code Breakers at all radio intelligence centers collaborated to compile and share lists of identified additives and code groups any moment of Brilliance or innovation was part of a vast Cooperative process codes are not deciphered by lone individuals noted Liza Mundy in her best-selling 2017 book code girls but by collectives of individuals exchanging fragments of insights and observations they have Acquired and retained sparkling tidbits of numbers and other useful items they've stored in their minds like magpies details they recall while peering over each other's shoulders highlighting patterns that eventually become the key to cracking the code as the identification of more additives and code groups progressed this information aided in discovering further additives and code groups the work was accumulative greatly aided by meticulous record-keeping of a vast collection of intercepted messages identified additives and deciphered code groups the employment of rudimentary data processing devices such as punchers sorters and tabulators also expedited the process once additives were removed from an intercepted message the exposed code groups were hand punched on IBM cards logged and the cards were hand sorted the meaning of deciphered code groups was also archived decoded messages were manually noted on index cards with key information emphasized multiple copies of the cards were made and filed separately based on the highlighted information later when cryptanalysts were decrypting a message they could recall a similar message and have a method to retrieve it the more messages that were intercepted and processed the more data was collected and the task gradually became easier however the notion that these codes were eventually cracked allowing Americans to read entire messages is incorrect the Japanese introduced the original jn25 operational code in June 1939 which was significantly more complex than its predecessor it took the Americans more than a year to decrypt any substantial content but by November 1940 they started extracting coherent text from jn25 intercepts however in December 1940 the Japanese launched a revised version jn25a which disrupted the progress of U.S cryptanalysts they couldn't decipher anything in the revised code until late 1941. by December 1941 American cryptanalysts could decipher less than 10 percent of the Japanese code groups messages that didn't contain any of the decrypted code groups would remain in entirely unintelligible thus in The crucial months leading up to Pearl Harbor Navy radio intelligence was limited to traffic analysis and Direction finding on December 4th 1941 as the Japanese carrier Strike Force was approaching the Hawaiian Islands the Japanese introduced yet another revised version of jn25 in the aftermath of the Pearl Harbor attack the U.S Navy restructured its code breaking operations appointing rochefort's Pearl Harbor unit as the lead in the jn-25b operation prior to this rochefort station was tackling other Japanese codes while stations in Washington DC and the Philippines worked on jn25 up until then the stations in Washington DC and the Philippines had made minimal progress into jn25 although they had uncovered the structure of the code and deciphered several thousand code groups they were unable to fully interpret Japanese intercepts the rapid and large-scale victories of the Japanese in the initial weeks of the war left rochefort and his team shocked aided by Washington and Cavite they intensified their efforts against jn-25 by April 1942 just a month before the battle of the Coral Sea and two months before the Battle of Midway rochefort's cryptanalysts had deciphered about one-fifth of the code groups in the jn-25b code this proved to be sufficient through a combination of traffic analysis Direction finding Snippets of decrypted message traffic and their understanding of the Japanese language military culture capabilities and strategic intentions the Americans managed to unearth vital details of Japan's Port Moresby operation more importantly they detected the planning of a larger operation which later turned out to be an invasion of Midway traffic analysis and Direction finding aided in identifying and locating units that were preparing for the operation while cryptanalysis brought to light intriguing fragments of movement orders Supply requests casualty T reports and other operational messages linguists and intelligence analysts meticulously examine the partial decrypts connecting the dots and filling in as many gaps as possible rochefort in particular was skilled at deducing Japanese intentions from the scant clues at hand Pacific Fleet intelligence Chief Edwin Layton later claimed that rochefort's intuitive knack for piecing together seemingly unrelated information in partially decrypted enemy messages and converting the puzzle into an accurate depiction of enemy intentions was instrumental in the American victory at the Battle of the Coral Sea this battle also strengthened Pacific Fleet Commander Chester nimitz's confidence in radio intelligence even while the battle of the Coral Sea was underway rocheford and his team were striving to unveil the specifics of the next major operation by mid-may they were deciphering up to 40 percent of JN 25 code groups as the solved groups tended to be the ones most frequently used used cryptanalysts could determine the meaning of or at least make a reasonably educated guess about a significant percentage of intercepted messages however only a portion of the Japanese radio traffic was intercepted at that stage of the war the sheer volume of messages being transmitted was so high that the Americans couldn't intercept enough to paint a comprehensive picture of Japanese plans in the month leading up to Midway when the Americans were eager to extract further details about Japanese plans Navy radio operators intercepted no more than 60 percent of Japanese traffic and cryptanalysts decoded parts of just 40 percent of the messages captured throughout May rochefort's team gradually began to comprehend the structure of the Japanese Midway operation intelligence analysts were receiving indications in seemingly unremarkable fragments the volume of message traffic was extraordinarily high and traffic analysis located key Japanese Fleet units and home Waters messages that were partially decoded describe the amalgamation of several Japanese carrier groups into a single striking Force other messages arranged refueling Rendezvous points ordered destroyers to join a carrier striking Force shortened Shipyard periods mentioned a landing and an occupation force and requested charts for the aleutians in the area around Midway each piece of information served as another piece in the enormous puzzle that rochefort and his team were diligently assembling no message was fully understood yet words or phrases from hundreds of messages information from traffic analysis and insights from past Japanese operations were meticulously woven together to form a discernible image of Japanese Intentions by mid-may rochefort could definitively state that the powerful second Fleet of the Japanese Navy was mustering an invasion Force at Saipan meanwhile at least four massive carriers the akagi kaga hear you and soar you were scheduled to convene in Japan's Inland Sea then set course for an undisclosed destination after May 21st leveraging the geographic designator they knew had been used in Prior messages to signify Midway the Americans were almost certain that Midway was the intended target this was agreed upon by both Nimitz and Admiral King in Washington while there was always the possibility that some of the dec deciphered information was part of a Japanese deception scheme Nimitz was prepared to act based on rochefort's assessment however rochefort had yet to discover the planned dates of the Japanese assault without knowing when the Japanese force planned to strike Midway Nimitz would be unable to correctly position his three carriers thus during the last week of May rochefort's team began a thorough re-examination of all messages intercepted between May 19th and 20th while these messages had already been deciphered Parts remained unsolved hidden within the still-coded segments was the date and time of the attack on May 25th the Americans Unearthed a partially decrypted message containing the code groups for Midway and attack along with a time date group that was separately encrypted using a complex and seldom used process that Navy cryptanalists had yet to crack amazingly two of roachford's cryptanalyst Joseph Finnegan and Wesley Wright worked through the night and managed to infer the structure of the table the Japan companies had used to encrypt the date time group The planned date for the Midway strike was June 4th while the aleutians would be hit on June 3rd this was the critical piece of information the U.S Navy could position its available Firepower the unscathed carriers Enterprise and Hornet and the damaged but still operational Yorktown Northwest of Midway ready to initiate a surprise air attack against yamamoto's carriers as soon as they could be identified by the evening of June 4th American Carrier airstrikes had obliterated all four of the Japanese carriers this American victory would not have been possible without the essential contributions of the radio intelligence units underplaying one of the war's greatest triumphs rochefort simply stated we felt that we had earned our pay [Music] thanks for watching Remember to like And subscribe see you soon [Music]

Channel: Hidden History

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Keywords: hidden history, ww2, battle of midway, codebreakers, ww2 codebreaking, ww2 naval codebreakers, American codebreaking ww2, Joseph rochefort, midway codes, midway, midway ww2, mark felton, dark seas, world war 2, wwii, ww2 documentary, battle of midway documentary, John ford midway, codebreaking ww2, Bletchley park, Japanese naval codes, navy codebreaking, codebreaking midway, ww2 intelligence, enigma, warships, navy, us navy ww2, The codebreakers that won the battle of midway

Id: oEfZBsl5f7s

Length: 28min 14sec (1694 seconds)

Published: Thu Jun 08 2023