Why was the Morse code invented?

It had been used to communicates

Morse Code allowed letters, numbers, and punctuation to be transmitted as long and short 'clicks' over railroad telegraph lines to quickly communicate information before the telephone was invented.

By RogerTango:

Also, the tone of a CW signal is much easier to identify with weak signals or a lot of interference. A Morse code tone only needs about 50 hertz of audio bandwith, a human voice requires about 1,000 hertz to be understandable. Morse Code is also a much more efficient mode of transmitting on radio when using limited RF power. HTH, Andrew