The Idea
In 1942, the US Military attempted to make use of the beautiful languages of the Native Americans as a means of secret communication. While reading an article about these plans, Philip Johnston came up with the idea to utilize the Navajo language, a complex and mostly unwritten language, as the basis of a code for World War II.
The use of Native languages had been used in the first World War, but not extensively. Because of this, the Marine Corps were hesitant to agree to Philip Johnston's plan. However, Johnston was able to convince them, leading to the creation of the "Unbreakable Code"