Sensitive messages have always been jealously guarded to ensure their privacy and security, never more so than in times of conflict.  However, the air, airtime and airspace are open and permeable, available and exposed, as are the transmission technologies which propagate them. The solution to such vulnerability is encryption, the rendering of the unambiguous and compressed into a cryptic form, publicly flaunting itself but impenetrable without a key.

The Romeo Alpha Foxtrot (Royal Air Force) held back whilst the Luftwaffe destroyed the city of Coventry in order not to give the Enigma Machine code breakers game away, a sacrifice that subsequently sealed the demise of the Afrika Corps through intercepted intelligence, but also initiated the horrific reprisal air-raids on Dresden. 

Across the Atlantic, US army communications were conducted in the unique and modern alphabet of the Cherokee Nation ~ a tongue difficult for the enemy to acquire.  In London, at the outbreak of hostilities the BBC panicked over the real possibility of Oxbridge trained Germans broadcasting ersatz programmes in perfect King’s English.  Their solution was to install Wilfred Pickles as the voice of London Calling.  Pickles, a Yorkshireman broke the mould of BBC voice types, with his broad northern accent, impossible even for a Home Counties resident to copy and perhaps understand, in this instance encrypting not the message per se but the vector of delivery.