Indian languages were virtually unknown to Europe and Japan, which made it a perfect code. A code that is based on a known language is much easier to crack than a code that is not and because of this, the United States saw a huge success rate with their code. Hitler had found out about this code and before the outbreak of WWII, he sent 30 anthropologists to the United States to research and learn the Indian language. One thing that made this feat near impossible was the fact that there are hundreds of different dialects that exist. In addition, since there was no written literature, it was near impossible for non-speakers to learn anything, especially different tones used by many tribes. This venture turned out to be unsuccessful and added strength to the reasons for using it as a code.
Some may ask, "Well it would be easy for the enemy to capture an Indian and have him/her translate messages so why didn't that work?" The answer to this question is perplexing until you dig a little deeper into the code itself. Cryptographers within the military brainstormed about this situation and created a solution of adding an additional layer of alphabet code to prevent interception by native speakers not trained as Code Talkers, in the event of their capture. Though the Navajo spoken code was not very strong by cryptographic standards of its time, it was never broken. The closest this code ever got to being broken was when the Japanese captured Joe Kieyoomia in the Phillipines in 1941. Kieyoomia was a Navajo Seargeant in the Army at time of capture and was forced to interpret radio messages. He told his capturers that he was unable to make sense of the code and was then tortured. Some believe that the code could have been broken if Kieyoomia's knowledge was exploited more effectively by the Japanese cryptologists.
To recruit for such an undertaking, the United States posted signs on most Navajo Reservations asking for help from any Navajo men who were willing.
