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Guest post by IT3 Kevin M. Stehr
Albert Einstein said, “The only source of knowledge is experience.” This is especially true in looking at United States Naval Intelligence during its formative years following WWI through WWII. Applicable lessons can be learned from the events of this era and the people that were a part of them; there should be examination of not just US Naval intelligence efforts, but also the efforts done by Germany and Japan as well.

Although in recent history, much has been said about the British efforts in deciphering the Enigma Code utilized by the Nazis in WWII, less well known is the efforts by US Naval Intelligence to break the 4-rotar enigma codes, code named Shark, that were used several years later. Set up in Dayton, Ohio, a team led by a civilian, Joe Desch, would take on the incredible challenge of creating an American Bombe that would be even more automated than the one used by Alan Turing and the team at Bletchley Park, but also able to break an even more complex cipher that could determine the Battle of the Atlantic; there was nothing more important to allied victory in Europe than the supply line that existed between America and Great Britain, but by 1942, the Germans had added a fourth rotor to their Enigma machines, and were planning a major U-Boat offensive in the spring of 1943. British intelligence had made no inroad in to breaking the more complicated code, so the US Navy was determined to create a Bombe to break the code, which was accomplished in the summer of 1943.

The first thing that should be noted about the efforts made by American Naval Intelligence in developing their own code breaking Bombe, is that prior to 1942, Alastair Denniston, head of the Government Code and Cipher School at Bletchley Park, gave an invitation to America’s top code breaker, Agnes Driscoll and Captain Laurence Safford, head of the Navy’s Code breaking operations in 1941, to visit Bletchley Park and examine the Turing Machines and the progress made by the British. Both Driscoll and Safford turned down the offer. Reason behind Driscoll’s decision lay in the fact that she had already made progress in breaking in to the Japanese Codes in the spring of 1930. Driscoll’s decline led to uneasy tensions between both the British and US Intelligence services that led to errors is War Time relations on both sides; The British withheld information that would have helped Americans develop their Bombe which could have been implemented on time.  Driscoll’s overconfidence led to a breakdown in communications that only hindered the Allie’s efforts to defeat Germany’s U-Boats; there was period of 10 months where Germany’s Wolf Packs (groups of U-Boats) were sinking many supply ships unhindered by the Allies. Aside from the lack of sharing technological advancements, the British initially withheld known cribs; these are key phrases or words that cryptanalysts use to help break a code.

A problem that developed even after both the American and British bombes were in production in mid 1943 was that the Allies were not able decrypt the enigma transmission in a timely manner to provide valuable intelligence, and when the 4-rotor Enigma code was being used there are a 10 month period where neither the British nor the Americans were able to decipher it. Eventually, the British had to admit they were not able to make any progress with the new 4-rotor Enigma code, and with the large number of Allied supplies being sunk (100,00 tons would be sunk in 1943), they had to rely on the American bombe to crack the new code, and decided to had over the known German cribs to their ally across the Atlantic. After the first bombes were used in Dayton or at Bletchley Park, it would take as much as 600 hours before full transmission could be completely decrypted, but by the end of 1943 with a hundred and twenty machines running at the annex in Washington, that time was shrunk to only eighteen hours, thus making the decrypted messages much more valuable. By the end of August 1943, the number of U-Boats had gone from 120 to a mere 40. Predictability of how the Nazi began and ended their communications made their code easier to crack than if they had randomized their greetings or endings.

Another important fact about the construction of the American bombe and its implementation is the role of the WAVES (Women Accepted for Voluntary Emergency Service). By spring of 1943, Joe Desch and his team at Building 26, were ready to mass-produce their own bombes, but needed a reliable, top quality workforce.  Able to recruit better candidates than its Army counterpart, the WAVES operated in secret first Dayton, Oh, and later at the Navy Communications Annex in Washington D.C. The American bombes, they constructed operated without much of hitch, an achievement only made possible the tireless efforts of both the WAVES and Joe Desch’s team; After Desch was able to create credible results with two different machines, the WAVES were brought in to assemble each part independently in Dayton in separate rooms so no one would know the full scale of what they were building. Also, when the operation moved to Washington D.C. and German traffic was to be decoded, operating in the rooms that housed the bombes were hot to the point of many of WAVES needing smelling salts, and several times, wheels on the machine flew off barely missing their female attendants. It is also important to know that the WAVES were held to the same standards as men in terms of security; they were informed that they would face a firing squad if they mentioned any aspect or their work in Dayton and to their credit, all kept quiet about their part on construction the American bombes.

The role that WAVES played in Dayton demonstrates a different aspect of intelligence work; with a properly motivated, disciplined staff, and clear direction given their superiors, any group can achieve their goal. Many initially scoffed at the idea of women being used in an intense, secretive atmosphere due to the belief that they would be prone to gossip about their work to anyone. In the present, the US Navy and the military in general should keep in mind that it is less about the gender of the recruits, and more about how motivated they are by their superiors. Technology is only as useful as the people who are running the machines.

A less talked about aspect of the intelligence war in Europe during WWII is the responses that Germany made to heighten the security of their Enigma communications. Although the addition of the fourth rotor in 1942 expanded the complexity of their communications, many of the German radio communications still contained the same greetings or endings, which provided cribs that could be used to decipher their communications. The cribs were given to the American bombe operators by British intelligence and the teams of WAVES at the annex in Washington were able to intercept and read the U-Boat communications so efficiently by late 1943 in to 1944 that the Nazis were losing more U-Boats than they could manufacture and the supply convoys were reaching British shores with greater success.  Germany’s downfall was ultimately there over confidence in Enigma’s perceived indecipherable complexity and lax security procedures.

There was also an inherent weakness in the German U-Boat operations; Admiral Donitz, who was the supreme Admiral of the German Navy, maintained a strict command of the U-Boats from on central location forced him to use High Frequency radio transmissions that are easier to intercept than short wave radio transmissions; it should also be noted that Nazi U-Boats did contain short wave radios. Donitz was also known to send more frequent communications on a daily basis to the U-Boats that lead to a large amount of traffic. The lack of trust in his commanders who had better on-scene intelligence, and the micro managing of his wolf packs was a leading factor in how the Enigma code was eventually broken. In contrast, if you look at the American Navy operations in the Pacific (where the US Navy operated exclusively), there many more relay stations at key point such as Guam and the Philippines which meant that they were not handicapped in using long range high frequency radio transmissions that are easier to intercept. Trusting your commanders in the field is as important to intelligence security as the technology that you use.

In shifting focus from the European theatre to the Pacific, the first that should be mentioned is that both the US and the Japanese were gathering intelligence on one another long before 1941; initial efforts by the US code-breakers to decrypt secure Japanese communications began as early as 1923 and surveillance on the US by Japanese agents was taking place by 1933. During this prewar time, Lieutenant Commander Miyazaki Toshio had entered the United States as a language student at Stanford, but soon relocated to Los Angeles and began running a former enlisted sailor to gain information on US ships. The simple lesson here is that when the use of spies is used in preparation for war, it should always be assumed that the enemy is doing the same thing.

Important to know about Japanese attaches who were also studying their future opponents in the US is that they were fluent in English, but there were only a handful of American Naval personal who were fluent in Japanese. Also, Joseph Rochefort and cryptanalysts at Hypo only consisted of 29 members prior to 1941, which put them at a disadvantage in being able to produce real time intelligence similar to what was going on in the European theatre with the Enigma code. In contrast by the end of 1943, there was over a thousand being used to break the JN-25 code. Commander Joseph Rochefort, head of Hypo, the cryptanalyst station in Hawaii, and his team were unable to know for certain where the Japanese carrier groups were; false intelligence that was received made it seem like the carriers were still in Japan, but they were in fact silent and heading to Pearl Harbor in 1941.

During May 1942, analysts at Hypo discovered that Operation MO, was the Japanese plan to take Port Moresby and Tulagi in the South Pacific. The Battle of Coral Sea is talked about mostly for it being the first naval engagement between aircraft carries, but it should also be mentioned that there is also an intelligence error that both the Japanese and American forces committed; they did not receive correct reconnaissance information. A minor group of Japanese cruisers and gunboats was incorrectly identified as a two carriers and several heavy cruisers, and only one of three cruisers that were part of the Australian part of the Allied force was correctly identified by the Japanese.

In some cases, it is not always the skill of the intelligence community that accomplishes in revealing an enemy’s plans; the enemy’s own lapse is security procedures. The Japanese would always take the security precaution of changing their code right before they maneuvered for an attack to frustrate cryptanalysts that were listening to traffic; the other thing they would do right before their infamous attack on Dec 7, 1941 is that they would go silent on their radio communications. However, because they still relied on dispersing they code in booklets, they failed to change the code before the American cryptanalysts discovered Yamamoto’s plans to attack Midway; the code would be changed on May 28, less than a week before the attack, but after their plans were discovered by cryptanalysts at both Hawaii and Melbourne, Australia.

The lead up to Midway provides another lesson in regards to intelligence work. It isn’t just the gathering and decrypting of information that matters, but also what actions do those who receive that information take. Rochefort, and his team at Hawaii were the first to intercept that traffic from the Japanese about the plan to strike at Midway, but they also knew that an attack was planned for the Aleutian Islands at the same time. Most of those at ONI in Washington believed that Yamamoto might attack as far east as the western coast of the United States, or the Aleutian Islands. Due to his time in Japan prior to the outbreak of the war in the Pacific, Rochefort knew that neither option was what the intended target by the Japanese; however Rochefort needed a way to prove his point to his superiors, especially Admiral Nimitz, that he was correct. False information that fresh water was running low at midway was given to the Japanese which was later identified by cryptanalysts in a decrypted message which reinforced that the attack would be at Midway. Knowing where Yamamoto planned to attack, Admiral Nimitz set an ambush at Midway, which would ultimately be the deciding battle of the Pacific and force the Japanese to play defense for rest of the war.

The aftermath of Midway in the United States highlights another important lesson that is perhaps even more relevant in modern times. On June 7, Commander Arthur H. McCollum read in the Chicago Tribune the same intelligence information that had been sent to Admiral Nimitz including how Commander Rochefort and the Hypo team had cracked the Japanese code to know where the Japanese would strike. Media scrutiny existed and continues to exist since the formative years of US Naval Intelligence, and as reported by Captain W.J. Holmes in narrative to the Chief of Naval Operations in 1945 “In war and in peace it can be expected that some newspaper will publish anything that makes a good story regardless of the ultimate cost of that story in blood and treasure” (SRH-120). History proved then, and continues to prove even today that the media  (televised news, online blogs, Youtube channels, etc.) are will to compromise the lives of those who serve, for their own personal benefit. What those in the media fail to fully comprehend is how much information they are providing our enemy; one of the main methods that the Japanese used to study American English and movement of our fleet was reading American Newspapers. Importantly, following the media scrutiny of the Battle of Midway, the Japanese changed their code, making it much more difficult for Allied cryptanalysts to decrypt their communications. Intelligence officials need to follow the same advice given by Captain Holmes to wisely choose excellent Public Relations Officers to disseminate information to the press.

The lesson from WWII and the preceding decades that led up to it are still resonant today. There is much more media scrutiny today thanks to the huge leaps in technology (cell phones, wireless technology, camera phones, etc.) and it is imperative that the intelligence community learns to manage them. Although America is a great country, it would be wise to not let ourselves think that equals invincibility as the Nazis did. Moreover, it is of the utmost importance that those with command authority not forget that it is not simply enough to have the best technology available, but also there must be a heavy emphasis on well-trained individuals. Finally, in an age of globalization,  let a lesson be learned from Agnes Driscoll to not scorn the offer of help from others and cause unneeded friction amongst those the US would consider allies.


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Petty Officer Stehr – Thank you for allowing us to share you work!

Petty Officer Stehr completed IT A-School in February 2017 and is waiting for orders to his first duty station. Before he enlisted, he worked as an educator in Texas from 2012 to 2016.  He was raised in Texas.