Of the many top secret operations conducted by secret service agents in World War II, there is no doubt that the breaking of the German Enigma code was the one that gave the Allies the greatest strategic advantage in the war. But the task of finally decoding this highly complex system was not without a lot of effort of the finest minds that could be put against the task. It was a massive operation at times requiring the services of over 500 people all working in absolute secrecy at Bletchley Park in Great Britain.
The task of breaking coded German communications began as early as 1938. At first the lower level codes were not difficult as they depended on coding schemes that the Germans had been using for decades. But as war approached, the complexity as well as the quantity of coded messages presented a serious challenge to secret service agents in World War II. The new code was nicknamed Enigma because it was so difficult to decrypt. It was a machine generated code using mathematical ciphers to make each transmission very difficult to decode without the necessary equipment at hand.
Throughout World War II, there was another front of the battle that went on along with the open warfare and that was the military objective of capturing German Enigma decoding machines. Stories of the capture of the machines or coding books to help Allied secret service agents to break the Enigma code are legendary. The quest to conquer these codes was one of the most monumental efforts that was mounted throughout the conflict and yet it was one that was conducted in such complete secrecy that the German intelligence community never realized the code was in danger of being broken.
The nonstop effort to break the Enigma code yielded success steadily but very slowly. The top secret project to crack this code at Bletchley Park was named Ultra. Even when the code was understood, the process of decrypting a message took hours for each Ultra agent calling for long and tedious effort. While not all decrypted messages yielded real military treasures, the strategic advantage of being able to “listen in” on the messages being sent between German military planners was what made the difference in the Allies ability to stay one step ahead of the Nazi’s and eventually win World War II.
Along with the tedious effort that each decryption task called for, the process of collecting German communications to feed the Ultra project was difficult and sometimes unreliable. Allied intelligence agencies staffed thousands of intercept stations all over Europe. The Germans were crafty in how they constantly changed frequencies, or shifted how and where they sent messages from to keep their enemies guessing. The task of staying on top of German communications methods to intercept Enigma coded messages was as difficult as the decrypting process itself.
The difficulty of learning German intelligence secrets threatened to become too overwhelming as the tempo of the war picked up and the number of communications being intercepted went from a few dozen to hundreds a day. One of the huge breakthroughs of the war effort came when British Engineers Alan Turing and Tommy Flowers created “The Colossus”, a precursor to the modern mainframe computer that made it possible to accurately break hundreds of encrypted messages each day without the intense manual effort. With The Colossus as part of our strategic military advantage, Allied military planners had what they needed to know well in advance where Hitler was going to strike and to determine to what extent the Axis powers were prepared for invasion plans being devised by the United States, Britain and their allies.
Many of the great stories of how we were able to distract German military movements and cause Hitler to send his troops to the wrong location were made possible by the knowledge we got from breaking the Enigma code. That one secret service accomplishment may be just as significant a scientific breakthrough that brought an early end to World War II as the development of the atomic bomb.