"The Navajo Code Talkers" by Doris Paul, 1974.
Currently binge reading on the WW2 Navajo Code Talkers that served with the Marines in the PTO. This is an older book about an absolutely fascinating piece of American history. Full disclosure - I felt myself flinching at times when the author describes the treatment of the Navajo people by the US government because I knew a shaming was about to be dealt. Instead the author lays the historical fact and for background to the story, and moves ahead.