Why did armies develop codes and ciphers after adopting wireless telegraphy?

Armies developed codes and ciphers after adopting wireless telegraphy because the technology lacked inherent secrecy. Unlike wired systems, wireless signals were broadcast through the air, meaning messages could be intercepted and heard by enemy forces as easily as by friendly ones.1

To maintain operational security, military organizations were forced to implement extensive and complicated codes and ciphers as essential components of their signaling procedures. This necessity triggered an ongoing struggle between cryptographers and cryptanalysts, which became a defining factor in the military application of radio technology throughout the 20th century.1