Nations at peace and at war have always attempted to intercept the communications of other nations for intelligence purposes. In May, 1916, Yardley, a state-department clerk, intercepted a coded cable from New York to the White House. Yardley broke the code within two hours and a year later presented "Solution of American Diplomatic Codes" to his superior David Salmon. According to Bamford, Salmon asked if Yardley thought that British code experts could also break American cryptographic codes. Yardley's answer to Salmon has since become a maxim for cryptographers: "I always assume that what is in the power of one man is in the power of another."

 
Index

Between the World Wars:
1920 - 1941

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It sure is dark in here!
 

 
      

Regardless of the value placed on intelligence during the war, the U.S. military followed it's normal pattern of demobilizing forces in peace time, to include intelligence personnel. The intelligence personnel in the AEF (Radio Intelligence Section) and MI-8 were demobilized, with the officers going into the newly crafted 'MI Officers Reserve Corps'. Active duty intelligence slots were filled by detail, it being assumed that intelligence work was a function of command and could be performed by any Regular Army officer. MAJ Van Deman and part of his MI-8 staff survived the demobilization by being transferred to the State Department as civilians. In August 1919 Herbert Yardley moved the 'Black Chamber' (MI-8) to New York. (Black Chamber was an old French phrase for any government agency that opens and reads mail.)
« « An rare glimpse of the inner workings of the Black Chamber

When General Pershing became the Army Chief of Staff in 1920, he used his former AEF staff organization as a model for the General Staff. There were now a G1, G2, G3, and G4 of the Army. Unfortunately, G2 wasn't and equal partner. The Military Intelligence Division of the Army Staff was cut back to 20 officers. Due to Congressionally-imposed restrictions on the number of general officers permitted to serve on the General Staff, the G2/Military Intelligence Division was normally headed by a colonel while the other Division's had a General officer as their head.

The 1920's saw two more significant technological milestones - in 1921 the first electronically-transmitted photograph (facsimile) was sent by Western Union and in 1927 the first television is demonstrated.

Although the responsibility for Army code and cipher compilation transferred to the Signal Corps in 1920, the MI-8's code and cipher compilation solution section continued as a covert cryptanalytic agency jointly funded by the War and State Departments. Still under Yardley's control, the MI-8 scored a number of significant triumphs in the 1920's. Most notable being its managing to decrypt the Japanese diplomatic code in time to strengthen the U.S. negotiating position during the Washington Peace Conference.

In August 1921 an agreement was reached between the Military Intelligence Division and the Signal Corps which consolidated code and cipher compilation under the Office of the Chief Signal Officer and left to the Cipher Bureau (MI-8) the job of code and cipher breaking.

On 30 June 1929 the MI-8 (Black Chamber) was discontinued due to two factors. The Army had come to the conclusion that Yardley's small operation, with its aging civilian staff, was not well suited to meeting the War Departments future needs. At the same time, a new Secretary of State, Henry L. Stinson (*see note), decided that decoding of foreign diplomatic communications was unethical. President Hoover apparently agreed with Stinson's alleged, yet oft-quoted statement "Gentlemen do not read each others mail" and returned the agency to a military orientation under the Army Signal Corps. The Military Intelligence Division transferred the solution functions and the files from MI-8 to the Signal Corps which formed a new section combining the duties of the defunct Cipher Bureau (MI-8) with those of the Code and Cipher Compilation Section, Office of the Chief Signal Officer.

The Signal Intelligence Service (SIS) was the new organization formed in 1929 to assume the functions of the disbanded MI-8 . Located in the Munitions Building in Washington D.C., it received its funding from MID and the Signal Corps. William Friedman served as its first director with one of his first tasks being the set up of an adequate program to provide training for officers in cryptology - known as the Signal Intelligence School . In July of 1934 a trainee of the Signal Intelligence School, 1LT W. Preston Corderman (who will become the first Chief of ASA), was made an instructor and the school, which had previously been conducted by Mr. Friedman and his civilian assistants, was formally organized as a separate section. From this time on the Signal Intelligence Service and school was staffed with military and civilian personnel.

The SIS's first decade of operation was during a time marked by reaction against the participation of the U.S. in world affairs. The War Department was hard hit and it was extremely difficult to obtain the necessary funds for expansion of SIGINT activities. This changed when the mounting European crisis of 1938, which culminated in Germany's invasion of Poland on 1 September 1939, accelerated the Army's planning for mobilization and expansion in the event of an emergency. In these plans the SIS was the first element in Washington's whole War Department establishment to be augmented in personnel, space and facilities. With the end of it's funding difficulties the SIS began it's expansion.

During the late 1930's five Signal Service Detachments, under the supervision of the Signal Officer in their respective Corps areas, were opened by the SIS. Their mission was to supply intercept material for training use at the Signal Intelligence School.In 1938 the Army's first tactical signals intercept unit, the 1st Radio Intelligence Company , located at Fort Monmouth, New Jersey, was formed.

The Early Signal Service Detachments
Note: It is very difficult to find information on these early stations -
1936 Quarry Heights, Panama Panama Detachment, 2nd Signal Service Company (Monitoring station No 4 Established in 1936 by Abraham Sinkov (SIS)
1936 Fort McKinely, Philippine Islands 10th Signal Service Det (Monitoring Station No 6) Station established by Lt Mark Rhodes (SIS) and a small radio detachment.
1938 Fort Sam Houston, Texas 7th Signal Service Det (Monitoring Station No 3)  
1938 Presidio (District of San Francisco), California 8th Signal Service Det (Monitoring station No 2) *Not to be confused with the irregular SIGINT station that was operated in the SF area in 1931. That station was a private initiative of Joseph Mauborgne, a colonel destined to rise to the post of commanding general of the Signal Corps before World War II, was assigned to the Presidio. He monitored and recorded Japanese radio traffic as early as 1931 and passed the intercepted coded messages to the Signal Intelligence Service in Washington. These intercepts became part of the earliest grist for the code breakers' mill that solved the Japanese machine cipher known as "Purple" in 1940. These intercepts contributed to the stream of intelligence, code named "Magic," that allowed the Allies unparalleled access to the enemy's plans and greatly contributed to the victory in the Pacific. By 1941, the Presidio had an official, but secret, monitoring station.
1938 Fort Shafter, Honolulu, Hawaii 9th Signal Service Det (Monitoring Station No 5) Established by Solomon Kullback (SIS) in 1936
15 Oct 1939 Fort Hunt, Virginia Monitoring station No. 7 On September 10, 1939, the National Park Service approved the occupation of the old hospital building at Fort Hunt by A 2nd Signal Service Company Detachment. On 15 October 1939 Lt Robert E. Schukraft and 26 men set up the monitoring station. They shared facilities with the Civilian Conservation Corps (CCC) camp already located there. May have moved to Mitchell Field, NY in 1946.
1930s Battery Cove, VA UI Signal Service Unit  
1939 Fort Hancock, NJ UI Signal Service Unit Sometimes referred to as a New York harbor unit

On 1 January 1939 the five Signal Service Detachments were reassigned to the newly activated 2nd Signal Service Company headquartered at Fort Monmouth. On 1 November 1939 the Headquarters of 2nd Signal Service Company was moved to the Munitions Building in Washington and co-located with the SIS. A small detachment of the Company remained at Fort Monmouth to expand the Cryptographic School.

The SIS/Army weren't the only service expanding their SIGINT stations in response to the war in Europe. In 1937 the Navy established the Mid-Pacific Strategic DF net. By 1941 it had stations at Cavite, PI; Guam; Samoa; Midway; Hawaii; and Dutch Harbor Alaska. The navy also opened "listening posts" on Bainbridge Island, Washington; Cheltenham, Maryland; Heeia, Oahu; Corregidor, PI; Guam; Imperial Beach, California; Amagansell, Long Island and Jupiter, Florida.

* An interesting side note. In the late 1930s, with the new Nazi Government of Germany becoming extremely strong and war becoming almost a certainty, Henry Stimpson was appointed to the position of Secretary of War by then President Franklin D. Roosevelt. Stimpson, realizing his stupidity of 1929, urged the President to name General William Donovan to create and head-up a new intelligence organization. General Donovan was widely known as "Wild Bill", a very astute organizer and leader of men. The intelligence organization that was formed by Donovan was the "Office of Strategic Services", commonly known as the OSS, later to become the Central Intelligence Agency (CIA).

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