Samuel Billison, who has died aged 78 in Arizona, was a respected educator and - because he had been a member - an expert on arguably the most secretive corps in the second World War, the Navajo "code talkers".
As a young Navajo, Billison dreamed of joining the Marines and enlisted the day he graduated from high school in 1943. At the end of the war, GI Bill in hand, he never returned to sheep-herding.
He earned a doctorate in education and studied law at the University of New Mexico, and went on to be a teacher, principal and administrator who helped reorganise the reservation education system under the Bureau of Indian Affairs.
He served on the Navajo Nation Council and in 1971, when their work was finally declassified, helped organise the Navajo Codetalkers Association.
In 1942 Japanese cryptographers were breaking US military codes seemingly at will. Philip Johnston, an engineer who had grown up as the son of missionaries on a Navajo reservation, suggested devising a code from the unwritten language, which was hardly spoken outside the Navajo Nation, and the Marines initially recruited 29 Navajos ages 16 to 18 and instructing them to come up with a code incomprehensible even to other Navajos outside the programme.
They gave aircraft the names of birds, naval vessels the names of fish, and land vehicles that of animals. For the words without Navajo equivalents, including place names such as Guadalcanal, the group spelled them out using a Navajo word for each letter.
Military officials worried initially that the intricate code was too unwieldy and time-consuming until an experiment showed that older US codes required two hours to encrypt, transmit and decipher while the Navajo code took only 2½ minutes.
The 421 code talkers trained during the war were assigned to frontline duty, using field radios and telephones to transmit orders during combat. Billison was sent to Iwo Jima, one of six code talkers who transmitted more than 800 error-free coded messages in a key 48 hours of the fierce, 36-day battle for the island . Two code talkers, along with 6,819 other Marines, died.
The never-broken Navajo code that, Billison liked to remind people, was devised "by a bunch of 16-year-old kids who were shepherds", was the principal communication used during the battle, in which 20,000 Japanese also died.
As the story of the code talkers emerged decades after the war in documentaries, books, articles and speeches by Billison and others, Hollywood became interested. He became a consultant on John Woo's 2002 film Windtalkers.
Samuel Billison: born 1926, died November 25th, 2004