The UK military recruiter mistook "cryptogamist" (algae expert) for "cryptogramist" and sent an algae expert to join the code breakers; he wasn't so useful until captured German papers arrived water-logged; with his expertise they salvaged them
American soldiers in the Pacific theater of WWII used passwords with the letter 'L'. Because the Japanese can't distinguish L and R, they would send out words like "Laura" and upon hearing back 'rorra', would "open fire'.
Johnny Cash was a military code breaker for the US Air Force.
Nüshu, a woman-only Chinese script, used it to write letters, poetry, and even autobiographies. Woman who knew Nüshu arguably had far more intellectual freedom because men could not read it.