Breaking the German Inigma Code had to be one of the top intelligence victories of all time. It was the communication code that the Germans used to communicate, and U.S. and British intelligence communities were able to break the code so that the Allies could know what the Germans were saying. Another intelligence victory was the planting of information regarding the actual location and time of the invasion that ended up being D-Day. Dis-information was sent to the Germans in the form of a deceased courier with elaborate plans for an invasion that was far away from Normandy France. Germans sent most of their military forces to that location in an effort to defeat the Allies during the invasion. A third major intelligence victory of WW2 was the "code-talkers". Navajo Indians spoke a language that NOBODY in the rest of the world understood. Their job was to continuously talk on the radio, mostly conversational stuff, then when there was real information to be sent the code talkers would slip that in. The Axis powers went nuts trying to decode a language which to them may as well have been from Mars. The Navajo Code Talkers were definitely heroes.