The internationally recognised radio distress signal, 'Mayday', came into the English language in 1923 in response to increased air and naval traffic over the Channel. Replacing the S.O.S call, Mayday, the phonetic pronunciation of M'aidez, French for 'Help me', is recognised by seafarers today.
The "mayday" procedure word was conceived as a distress call in the early 1920s by Frederick Stanley Mockford, officer-in-charge of radio at Croydon Airport, England. He had been asked to think of a word that would indicate distress and would easily be understood by all pilots and ground staff in an emergency.
There was a lot of air traffic between England and France in those days, and evidently there were enough international problems over the English Channel that both parties wanted to find a good distress signal that everyone would understand.