During the Battle of France in May 1940, the value of deciphered enemy communications started to emerge, especially from the German Army when field commanders filed situation reports to headquarters each day. This allowed the British commanders to check on their own information and build up a more accurate picture. This gave great confidence in the potential of this intelligence and greatly raised Bletchley's profile with the military.
In May 1940, several new prototypes of electromechanical machines, or Bombes, were completed, based on the original Polish idea, and initial results proved very promising as the operation of deciphering dramatically sped up. If messages were decrypted in a 24-hour window, this would provide invaluable information on enemy intent and threats, and allow defensive positions to be taken prior to any enemy offensive. The odds against breaking Enigma were a staggering 150 million to one, so it was unlikely this source of intelligence would come under suspicion as it was considered highly secure by the Axis.
Churchill had to use the limited resources he had at his disposal in the most effective way. He could only do that through the greater use of organizational and enemy intelligence. Knowing the extent of enemy preparation and activity would provide the necessary insight to where and how the enemy was likely to strike next. Armed with this, Churchill could then better target resources to meet the invasion threat.
Churchill knew the value of intelligence and was shaped by his previous experiences from the First World War. First, the lack of a central policy undermined coordination of resources and prolonged the UK's response as well as the war. Second, the lack of reliable intelligence proved a major undoing for him at Gallipoli in 1915, which crucified his career in the short term. Churchill's plan to defeat Turkey by sending in British warships and troops to stand off Constantinople failed miserably. As the troops hit the beaches at Gallipoli, without adequate ground intelligence, they had nowhere to go and were gunned down by the Turkish army that commanded the heights and overall terrain of the beaches.
As Churchill came to power in May 1940, he became aware of the secret establishment at Bletchley Park, which collected and deciphered encrypted enemy communications or Enigma codes under the overall command of Stewart Menzies, the director of Military Intelligence (MI6). Bletchley Park was opened in 1938 when the Government Codes & Ciphers School was moved there to test its suitability for warfare. The mansion was located midway between the Universities of Oxford and Cambridge, a fertile community and source of mathematicians and logicians, all ideal code-breaker candidates. Bletchley Park, commanded by Alastair Denniston, was given the cover name Station X, being the tenth of a large number of sites acquired by MI6 for its wartime operations.
Churchill was made aware of Bletchley and quickly recognized its potential. The necessary investments were made to further automate and scale the operation up. This was done through more Bombes and the influx of skilled staff into Hut 3, which dramatically optimized the operation. The operation was given the code name "Ultra," and then shrouded in a veil of security. A network of listening stations called "Y" Stations was set up to gather raw wireless signals for processing at Bletchley. The focus at Bletchley was not just on breaking the Enigma code, but as the volume of messages increased, putting a significance or priority on key messages going to chiefs of staff and Churchill. This proved extremely valuable for the recipients. However, a new cog in the operation was required, namely an interpretation unit, known as the Shadow OKH (German Army High Command) in Hut 3, which required the influx of skilled human resources. The emphasis was on pooling this information with previous messages to create an enormous bank of organized knowledge.