ナバホ語
In February 1942, a civilian named Philip Johnston came up with the idea of using the Navajo language as military code. Johnston, a missionaries' son, grew up on a reservation and understood the complexity of the Navajo language. By September 1942, the American government had recruited several hundred Native Americans who spoke both Navajo and English to translate English words into the Navajo language to foil enemy understanding. Often working behind enemy lines, the code talkers were commended for their bravery and gained respect from fellow soldiers. At its declassification in 1968, the code that these Navajo developed was the only oral military code that was not broken by an enemy.