Editing Optical telegraph (section)

====Development in France<!-- "France" required to avoid repeated heandin name per [[MOS:HEAD]] -->====
During 1790–1795, at the height of the [[French Revolution]], France needed a swift and reliable [[military communications]] system to thwart the war efforts of its enemies. France was surrounded by the forces of Britain, the Netherlands, [[Prussia]], Austria, and Spain, the cities of [[Marseille]] and [[Lyon]] were in revolt, and the [[History of the Royal Navy#Wars with France, 1690–1815|British Fleet]] held [[Toulon]]. The only advantage France held was the lack of cooperation between the allied forces due to their inadequate lines of communication.

In mid-1790, the Chappe brothers set about devising a system of communication that would allow the central government to receive intelligence and to transmit orders in the shortest possible time. Chappe considered many possible methods including audio and smoke. He even considered using electricity, but could not find insulation for the conductors that would withstand the high-voltage [[electrostatic generator|electrostatic sources]] available at the time.<ref>Patrice Flichy, ''Dynamics of Modern Communication'', p. 33, SAGE, 1995 {{ISBN|144622712X}}</ref><ref>Holzmann & Pehrson, p. 53</ref>

Chappe settled on an optical system and the first public demonstration occurred on 2 March 1791 between [[Brûlon]] and [[Parcé-sur-Sarthe|Parcé]], a distance of {{convert|16|km}}. The system consisted of a modified pendulum clock at each end with dials marked with ten numerals. The hands of the clocks almost certainly moved much faster than a normal clock. The hands of both clocks were set in motion at the same time with a synchronisation signal. Further signals indicated the time at which the dial should be read. The numbers sent were then looked up in a [[codebook]]. In their preliminary experiments over a shorter distance, the Chappes had banged a pan for synchronisation. In the demonstration, they used black and white panels observed with a telescope. The message to be sent was chosen by town officials at Brûlon and sent by René Chappe to Claude Chappe at Parcé who had no pre-knowledge of the message. The message read "si vous réussissez, vous serez bientôt couverts de gloire" (If you succeed, you will soon bask in glory). It was only later that Chappe realised that he could dispense with the clocks and the synchronisation system itself could be used to pass messages.<ref>Holzmann & Pehrson, pp. 53–55</ref>

The Chappes carried out experiments during the next two years, and on two occasions their apparatus at [[Place de l'Étoile]], [[Paris]] was destroyed by mobs who thought they were communicating with [[Chouannerie|royalist]] forces. Their cause was assisted by Ignace Chappe being elected to the [[National Legislative Assembly (France)|Legislative Assembly]]. In the summer of 1792 Claude was appointed ''Ingénieur-Télégraphiste'' and charged with establishing a line of stations between Paris and [[Lille]], a distance of 230 kilometres (about 143 miles). It was used to carry dispatches for the war between France and Austria. In 1794, it brought news of a French capture of [[Condé-sur-l'Escaut]] from the Austrians less than an hour after it occurred.<ref>[https://www.bbc.co.uk/news/magazine-22909590 How Napoleon's semaphore telegraph changed the world], BBC News, Hugh Schofield, 16 June 2013</ref><!-- Note: this BBC source tells this story well, and supports the Lille and Conde statements, but was not used for the whole section, which remains 'unreferenced' --> The first symbol of a message to Lille would pass through 15 stations in only nine minutes. The speed of the line varied with the weather, but the line to Lille typically transferred 36 symbols, a complete message, in about 32 minutes. Another line of 50 stations was completed in 1798, covering 488&nbsp;km between Paris and [[Strasbourg]].<ref>{{Cite web|url=https://ethw.org/w/images/1/17/Dilhac.pdf|title = Engineering and Technology History Wiki}}</ref> From 1803 on, the French also used the 3-arm Depillon semaphore at coastal locations to provide warning of British incursions.<ref name="Burns2004"/>

English military engineer [[Sir William Congreve, 1st Baronet|William Congreve]] observed that at the [[Battle of Menin (1793)|Battle of Vervik]] of 1793 French commanders directed their forces by using the sails of a prominent local windmill as an improvised signal station. Two of the four sails of the mill had been removed to resemble the arm of the new telegraph.<ref>{{cite book |last1=Gamble |first1=John |author1-link=John Gamble (priest) |title=An essay on the different modes of communication by signals |date=1797 |publisher=[[William Miller (British publisher)|William Miller]] |location=London |oclc=495253065 |page=66}}</ref><ref>{{cite journal |last1=ffoulkes |first1=Charles |author1-link=Charles ffoulkes |title=Notes on the Development of Signals Used for Military Purposes |journal=Journal of the Society for Army Historical Research |date=1943 |volume=22 |issue=85 |pages=20–27 |jstor=44219957 |url=https://www.jstor.org/stable/44219957 |issn=0037-9700}}</ref>