During World War II the Navajo volunteered and served with great distinction. The famous "code talkers" used native languages as an unbreakable code during various wars. The Choctaw performed a similar service during World War I, but have received virtually no recognition and their efforts have essentially been forgotten. An initial number of Navajo Code Talkers were augmented with Comanche, Cherokee, Navajo, Papago, Pima, and other Native Americans.
In addition to using native languages which usually were not accessible to the enemy, non-standard dialects and new vocabularies were invented in order to make decipherment impossible even when a native speaker was captured.