Immediately upon entering World War II, America faced the problem of its messages being intercepted by Germany, Italy, and Japan. As such, the American military needed to develop a code that couldn’t easily be broken. Early in 1942, Los Angeles civil engineer Philip Johnston proposed a solution. Having spent much of his youth on a Navajo reservation, and being one of the few non-Navajo people on Earth who understood the Navajo language, Johnston suggested the military recruit Navajos and use their language to communicate vital war information.