It's Unbreakable: 3 Interesting Facts About the Navajo Code Talkers of WWII
During WWII, the US government needed to devise a new way to communicate through codes. The military had been successful in using Native American languages during WWII, but after Germany and Japan sent students to the United States to learn those languages, the United States could no longer depend on the security of their old system of coding. Eventually, the US Army decided on the Navajo language to be their new system.