The electric telegraph was built in 1839 in the UK, by William Cooke and Charles Wheatstone. But it was scientists working separately in different countries who finally developed apparatus that used the electromagnetic effect to transmit coded signals.
Cooke having developed a telegraph, consisting of two dials of letters, working synchronously via a length of wire, and on which particular letters of the message were indicated by an electro-magnet and pointer. However he couldn't send signals over longer wires, say up to a mile.
He was sent by a colleague to Wheatstone and was dismayed to discover Wheatstone was also working on a similar device. Wheatstone managed to solve the problem of resistance in the longer wires with relays and, as Cooke's apparatus's mechanism was better made, they combined forces and patented the Cooke and Wheatstone apparatus in 1837.
At the same time Samuel Morse was developing his version of the telegraph in the United States and his code, used to send messages by switching the current off and on, was quickly adopted by Cooke and Wheatstone. The potential of telegraphy for commercial use was immediately obvious.
The first use of the electric telegraph for military purposes was one among many technical advances of the Crimean War (1854-1856) . Telegraph communications were fast, giving an army great advantages on the battlefield, in the same way that satellite communications do today. However, the forces' commanders were not the only ones to benefit from the speedy flow of information. The telegraph also enabled British businesses to control the flow of news and sustain their wealth and power.