Code talker
Native soldiers developed two types of Native American Code Talking (NACT). First developed by Choctaw in World War I, Type one NACT contained coded vocabulary, collections of words or phrases that were assigned to military subjects, within their languages. Type two NACT simply used existing Native languages. Both forms worked as codes because they were based on languages unknown to the enemy and, as the new codes were not based on mathematical processes as found in most code and cipher systems, the enemy had nothing to which to compare them.