In 1942, Philip Johnson suggested that the U.S. Marines use the Navajo language as a secret code. Johnson had grown up on an Navajo Reservation. The Navajo language had complex syntax, tonal qualities and dialect. Navajo was not a written language. Less than 30 non-Navajos understood it.

A Navajo code programme was established at Camp Pendleton at Oceanside, California. 29 Navajo Code Talkers were recruited. More than 450 frequently used military terms were given Navajo equivalents.

About 400 Navajos agents were trained to use the code. From these, 300 were active in the field. Navajo Code Talkers were a part of every major Marine assault during the Second World War.

Navajo soldiers were often at great risk from being shot in battle by their own side as they looked like Japanese, and often mistaken for one. The role of Navajo code breakers was kept a secret until 1968.

In December, 1981, President Ronald Reagan awarded the Navajo Code Talkers with a Certificate of Appreciation. 29 Code Breakers received Congressional Gold Medals in 2001 and the rest received Silver Medals.