In World War II, they were credited with making it possible to win the war in the Pacific: The Navajo Code talkers, whose work was top secret for 26 years after the war, have been celebrated with movies, medals, and even a special day, August 14.
The unique contributions of the all-Navajo 382nd Marine platoon were possible because they spoke one of the most complex — and obscure — languages in the world.
The Navajo language is from the Athabascan language family, about 44 separate North American languages spoken by indigenous people in Canada and Alaska, on the U.S. Pacific coast, and the U.S. Southwest.
Navajo is exceptionally complex. Even missionaries rarely achieved fluency. Philip Johnston, a non-Navajo civil engineer who proposed the Code Talkers program in 1942, stated that fewer than 30 non-Navajos in the world could "understand" Navajo. Johnston was born to missionaries on Navajo land and attended Navajo schools as a child. He was perhaps one of the most fluent non-Navajo speakers, but Code Talker Chester Nez once said that Johnston's accent and grasp of nuanced grammar were nonetheless imperfect.
Navajo has four tones in the language so that pitch changes the meaning of a single word. Each word is highly complex, using prefixes, suffixes and verb stems to convey full sentences. One Navajo verb can convey a complex thought: niltsaa ildiits'iili (linguistic markings are omitted here) can mean "I am repeatedly picking up small objects." Verbs can also convey such things as object shape. "Carry a round object" would be different than "Carry a flat object." Each verb has special conjugations for aspect, mood, and subject/object agreement.
Today Navajo is one of the healthiest Athabascan languages with 170,000 people telling the 2010 census that they spoke Navajo. In 1950s it was estimated that only 50,000 speakers existed.