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
Early in 1942,
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.
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.
The Navajo code talkers were commended for their skill, speed, and accuracy demonstrated throughout the war. At the Battle of Iwo Jima, Major Howard Connor, 5th Marine Division signal officer, had six Navajo code talkers working around the clock during the first two days of the battle. These six sent and received over 800 messages, all without error. Connor later stated, "Were it not for the Navajos, the Marines would never have taken
As the war progressed, additional code words were added on and incorporated program-wide. In other instances, informal short-cut code words were devised for a particular campaign and not disseminated beyond the area of operation. To ensure a consistent use of code terminologies throughout the Pacific Theater, representative code talkers of each of the U.S. Marine divisions met in
The deployment of the Navajo code talkers continued through the Korean War and after, until it was ended early in the Vietnam War. The Navajo code is the only spoken military code never to have been deciphered.