United States forces at Okinawa not only fought with the usual weapons of war, but also with a powerful code based on the Navajo language - the only code never broken by an enemy.
A pilot project for the code, which could quickly and securely send vital radio messages, began shortly after Pearl Harbor. The Marines recruited Navajos, many of whom were eager to serve the US in battle, to devise and eventually implement the code.
The complexities and nuances of the Navajo language - which essentially exists only in oral form - made it particularly well-suited for a code. The vowel "a," for example, can be pronounced at least 11 different ways, with different inflections indicating different words. The Marines capitalized on this subtlety of sound by keeping the code entirely oral; code words had to be memorized and were not written down.
The Navajo code-talkers gave the code logical connections to their language. Bombs, for example, reminded Navajos of eggs; thus they chose a-ye-shi, their word for eggs, as the code word for bomb. The Navajo word for frog, chal, described an amphibious assault.
The successfully trained Navajo code-talkers, who eventually numbered more than 300, participated in key Pacific battles. Details of their operations are now difficult to reconstruct, but the code-talkers have been credited as being instrumental in at least one victory. "Were it not for the Navajo code talkers, the Marines never would have taken Iwo Jima," noted Maj. Howard Conner, signal officer of the 5th Marine Division at Iwo Jima.
Although successful, the code-talkers created unforeseen problems. The sound of the code was sometimes mistaken for Japanese. Many marine units assigned bodyguards to protect code-talkers from confused Americans.