<P> Because Navajo has a complex grammar, it is not nearly mutually intelligible enough with even its closest relatives within the Na - Dene family to provide meaningful information . It was still an unwritten language, and Johnston thought Navajo could satisfy the military requirement for an undecipherable code . Navajo was spoken only on the Navajo lands of the American Southwest . Its syntax and tonal qualities, not to mention dialects, made it unintelligible to anyone without extensive exposure and training . One estimate indicates that at the outbreak of World War II, fewer than 30 non-Navajo could understand the language . </P> <P> Early in 1942, Johnston met with Major General Clayton B. Vogel, the commanding general of Amphibious Corps, Pacific Fleet, and his staff . Johnston staged tests under simulated combat conditions which demonstrated that Navajo men could encode, transmit, and decode a three - line English message in 20 seconds, versus the 30 minutes required by machines at that time . The idea was accepted, with Vogel recommending that the Marines recruit 200 Navajo . The first 29 Navajo recruits attended boot camp in May 1942 . This first group created the Navajo code at Camp Pendleton, Oceanside, California . </P> <P> The Navajo code was formally developed and modeled on the Joint Army / Navy Phonetic Alphabet that uses agreed - upon English words to represent letters . The Navajo Code Talkers were mainly Marines . As it was determined that phonetically spelling out all military terms letter by letter into words--while in combat--would be too time - consuming, some terms, concepts, tactics and instruments of modern warfare were given uniquely formal descriptive nomenclatures in Navajo (for example, the word for "shark" being used to refer to a destroyer, or "silver oak leaf" to the rank of lieutenant colonel). Several of these coinages, such as gofasters referring to running shoes or ink sticks for pens, entered Marine Corps vocabulary . They are commonly used today to refer to the appropriate objects . </P> <P> A codebook was developed to teach the many relevant words and concepts to new initiates . The text was for classroom purposes only, and was never to be taken into the field . The code talkers memorized all these variations and practiced their rapid use under stressful conditions during training . Uninitiated Navajo speakers would have no idea what the code talkers' messages meant; they would hear only truncated and disjointed strings of individual, unrelated nouns and verbs . </P>

Who were the windtalkers and what did they do