navajo code talkers wwII
Navajo Code Talkers (http://www.u-s-history.com/pages/h3981.html) Navajo marines designed a secret warfare code that foiled expert Japanese code breakers who had managed to crack army and navy codes. Its secret lay in the intricacy of the Navajo tongue, some of whose sounds were unique, and it had no symbols or alphabet. A regional language, it was relegated to the southwest U.S. alone.(http://www.u-s-history.com/pages/h3981.html)