This is a very cool video.
Apparently, there was code translating machines but they weren’t that fast. The “telegraphic” code words in the unwritten Navajo language, with their memorized meanings, meant that coms were very fast.
During WWI the Choctaw language was used for tactical messages. Meanwhile, Japan and Germany had sent people to these USA to study native languages! However, there was Navajo, which is really complicated.