Guadalcanal, Tarawa, Peleliu, Iwo Jima: the Navajo code talkers took part in every assault the U.S. Marines conducted in the Pacific from 1942 to 1945. They served in all six Marine divisions, Marine Raider battalions and Marine parachute units, transmitting messages by telephone and radio in their native language a code that the Japanese never broke.
The idea to use Navajo for secure communications came from Philip Johnston, the son of a missionary to the Navajos and one of the few non-Navajos who spoke their language fluently. Johnston, reared on the Navajo reservation, was a World War I veteran who knew of the military’s search for a code that would withstand all attempts to decipher it. He also knew that Native American languages notably Choctaw had been used in World War I to encode messages.
Johnston believed Navajo answered the military requirement for an undecipherable code because Navajo is an unwritten language of extreme complexity. Its syntax and tonal qualities, not to mention dialects, make it unintelligible to anyone without extensive exposure and training. It has no alphabet or symbols, and is spoken only on the Navajo lands of the American Southwest. One estimate indicates that less than 30 non-Navajos, none of them Japanese, could understand the language at the outbreak of World War II.
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Praise for their skill, speed and accuracy accrued throughout the war. At Iwo Jima, Major Howard Connor, 5th Marine Division signal officer, declared, “Were it not for the Navajos, the Marines would never have taken Iwo Jima.” Connor had six Navajo code talkers working around the clock during the first two days of the battle. Those six sent and received over 800 messages, all without error.
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Navajo remained potentially valuable as code even after the war. For that reason, the code talkers, whose skill and courage saved both American lives and military engagements, only recently earned recognition from the Government and the public.
Great link.
There also were Indian Code Talkers in WWI, from a number of different tribes.
One reason the Allies of WWI had such a hard time maintaining operational security was that during all the back-and-forth actions with the Germans, during each of the Huns' advances, they had been tapping the telephone lines and running a connection back to their lines. And with all the mud in the trenches, the phone lines all became a tangled and muddy mess, which made it impossible to tell the lines legitimately laid by the Allies from those patched in by the Germans.
Using the code talkers was one major reason the Allies' offensive operations became progressively more effective in the final months of the war.
World War I Code Talkers https://www.thenmusa.org/articles/world-war-i-code-talkers/