Signals Intelligence In World War II

Signals Intelligence in World War II: The Ancestor of Modern SIGINT
Signals Intelligence in World War II began as a defunct system that appeared to be doomed and offered little to no valuable intelligence to commanders at all echelons. The United States Army formed the Signal Intelligence Service (SIS) in 1930 in an effort to consolidate all Army cryptologic functions underneath the Signal Corps. The Army identified the need for the SIS following the dissolution of the War Departments Military Intelligence Division in New York the previous year. The initial success of the SIS in deciphering of Japanese radio transmissions was bittersweet due to the lack of a dissemination method for this classification of information. Senior officials only
received parts of the picture, resulting in the iconic Battle of Pearl Harbor. The first chief of the SIS, William F. Friedman, was later quoted on the subject stating, “each message represented only a single frame, so to speak, in a long motion picture film.” No one was in position to view the entire film.

Despite it’s early setbacks, the SIS continued its effort in establishing the importance of Signals Intelligence.
The SIS expanded its footprint and aligned its monitoring stations into a better position for the current wartime conditions. The SIS hired a large civilian workforce and constructed multiple buildings to hold the overflow workspace for their large employee base. The SIS also underwent a renaming period, initially changing to the Signal Security Division, but ultimately became the Signal Security Agency (SSA) in 1943. During this expansion, the SSA began looking at sharing their efforts with allies. The SSA opened a small detachment in Australia
to

work in a combined effort in the Southwest Pacific Area under the leadership of Brigadier General Spencer Akin. Despite this rapid expansion, the SSA still faced adversity due to a lack of personnel at key positions to identify what to collect. The SSA also had no control over the tactical signals intelligence units who worked for their supported commanders. The shortage of personnel at higher echelons and military regulations also resulted in the bottlenecking of information hampering their efforts. Unfortunately, the SSA was unable to present the importance of this work as justification due to the sensitivity of its classification.

Further issues continued to frustrate the Army due to its failures at advancements in the European and African fronts of the war. Land combat in Tunisia highlighted multiple deficiencies in the structuring of Army’s tactical signals intelligence organization. Divisional platoons could not effectively practice their specialty due to their required proximity to the front lines, the Signal Radio Intelligence Companies were too large and unmanageable to be used to effectively support corps requirements. Additionally, The volume of information being received was too much for the limited staff at the Army level to process. This led to further expansion with the Army turning to the British for aid in processing the volume of data. Secretary of War Henry L. Stimsons attorney, Alfred McCormack later commented on the matter stating, “except for whatever the Navy had been able to do, we have achieved no corresponding victory over the Japanese. To date, in the field of radio intelligence, we have met largely with failure.”

However, Mr. McCormack spoke too soon. Recent successful exploitations of Japanese Water Transport codes had begun to launch advancements in the exploitation of other systems. Additionally, the SSAs continued expansion allowed the organization to throw massive amounts of man-hours and IBM Machines against Japanese military cryptosystems in mid 1943. Shortly after Mr. McCormacks comment, the Arlington Hall workspace for the SSA had successfully mastered the main Japanese Army code, opening the floodgates holding back intelligence. Due to these successes, then Army Deputy Chief of Staff LTG Joseph McNarney forced the SSA back under the control of the Army’s Military Intelligence Division. This caused a rapid level of growth in both military and civilian efforts within the SSA and the construction of many more listening posts. These expansions yielded major results in the advancement of signals intelligence and solidified its place with the interception of Japanese communications warning American forces of the planned ambush known as The Battle of Midway.

In the European theatre, joint U.S. Army and British efforts produced many results. The revelation by the British of the secret to the German ENIGMA encryption devices as well as the establishment of Special Security Officers and Representatives to courier the intercepts, codenamed ULTRA, allowed the U.S. Army and the Army Air Force to solve the German threat. The Army sent officers to Special Branch in Bletchley Park to receive training to become SSOs. Special Branch provided these officers with a continuous amount of ULTRA intelligence to deliver to commanders in

Britain and in Europe.
ULTRA became the primary method of intelligence collection in Europe, and due to the dedication and skill of the SSOs appointed, remained a great secret in the war. General Dwight D. Eisenhower later wrote to the Chief of the British Secret Service, thanking him for the wealth of information provided by ULTRA. “The intelligence which has emanated from you before and during this campaign has been of priceless value to me. It has simplified my task as a commander enormously. It has saved thousands of British and American lives and, in no small way, contributed to the speed with which the enemy was routed and eventually forced to
surrender.”

In conclusion, the efforts of the United States Military as a whole, and the assistance of our allies resulted in possibly one of the most rapid transformations of the Intelligence Community. From the steadfast dedication of the SSD in the pacific theatre, and the extensive cooperation of the British in the advancements of ULTRA intelligence in Europe, signals intelligence evolved from being the trivial and frustrating collection discipline to being the primary method for collecting timely and accurate intelligence on all who would wish us harm. These endeavors have continued to today and will likely continue to yield benefits as technology continues to evolve allowing increasingly complex methods of technical communication.