Language /
Polish was chosen the HARDEST LANGUAGE in the world to learn... :D [1558]
Simplified basic rules on Polish vocative (there may be an exception here or there):
Thank you, Mafketisu. Very helpful.
because the Japanese probably didn't have any Navajo speakers or even any linguists who had knowledge of it
The Japanese had captured a couple of Navahoes who were not code talkers. The problem was, the captured people recognized the words, but didn't know what they meant. Navaho for turtle stood for a tank. Literal Navaho "Turkey Rain" sounds a bit like terrain when literally translated so turkey rain was terrain.
See nativewiki.org/Code_talker and
windtalkersthemovie.com/html/index.html
for good explanations.