Editing Electrical telegraph (section)

==Telegraphy in war==
The ability to send telegrams brought obvious advantages to those conducting war. Secret messages were encoded, so interception alone would not be sufficient for the opposing side to gain an advantage. There were also geographical constraints on intercepting the telegraph cables that improved security, however once radio telegraphy was developed interception became far more widespread.

===Crimean War===
The [[Crimean War]] was one of the first conflicts to use [[Telegraphy|telegraphs]] and was one of the first to be documented extensively. In 1854, the government in London created a military Telegraph Detachment for the Army commanded by an officer of the [[Royal Engineers]]. It was to comprise twenty-five men from the Royal Corps of Sappers & Miners trained by the Electric Telegraph Company to construct and work the first field electric telegraph.<ref>{{Citation |last=Roberts |first=Steven |title=Distant Writing A History of Telegraph Companies in Britain between 1838 and 1868: 16. Telegraph at War 1854–1868 |year=2012 |url=http://distantwriting.co.uk/telegraphwar.html}}</ref>

Journalistic recording of the war was provided by [[William Howard Russell]] (writing for ''[[The Times]]'' newspaper) with photographs by [[Roger Fenton]].{{sfn|Figes|2010|pp=306–309}} News from war correspondents kept the public of the nations involved in the war informed of the day-to-day events in a way that had not been possible in any previous war. After the French extended their telegraph lines to the coast of the Black Sea in late 1854, war news began reaching [[London]] in two days. When the British laid an underwater cable to the Crimean peninsula in April 1855, news reached London in a few hours. These prompt daily news reports energised British public opinion on the war, which brought down the government and led to Lord Palmerston becoming prime minister.{{sfn|Figes|2010|pp=304–311}}

===American Civil War===
During the [[American Civil War]] the telegraph proved its value as a tactical, operational, and strategic communication medium and an important contributor to Union victory.<ref>{{Citation |last=Hochfelder |first=David |title=Essential Civil WAR Curriculum: The Telegraph |publisher=Virginia Center for Civil War Studies at Virginia Tech |year=2019 |url=https://www.essentialcivilwarcurriculum.com/the-telegraph.html}}</ref> By contrast the Confederacy failed to make effective use of the South's much smaller telegraph network. Prior to the War the telegraph systems were primarily used in the commercial sector. Government buildings were not inter-connected with telegraph lines, but relied on runners to carry messages back and forth.{{sfn|Schwoch|2018}} Before the war the Government saw no need to connect lines within city limits, however, they did see the use in connections between cities. Washington D.C. being the hub of government, it had the most connections, but there were only a few lines running north and south out of the city.{{sfn|Schwoch|2018}} It was not until the Civil War that the government saw the true potential of the telegraph system. Soon after the shelling of [[Fort Sumter]], the South cut telegraph lines running into D.C., which put the city in a state of panic because they feared an immediate Southern invasion.{{sfn|Hochfelder|2012}}{{sfn|Schwoch|2018}}

Within 6 months of the start of the war, the [[U.S. Military Telegraph Corps]] (USMT) had laid approximately {{convert|300|mi|km}} of line. By war's end they had laid approximately {{convert|15000|mi|km}} of line, 8,000 for military and 5,000 for commercial use, and had handled approximately 6.5&nbsp;million messages. The telegraph was not only important for communication within the armed forces, but also in the civilian sector, helping political leaders to maintain control over their districts.{{sfn|Hochfelder|2012}}

Even before the war, the [[American Telegraph Company]] censored suspect messages informally to block aid to the secession movement. During the war, [[United States Secretary of War|Secretary of War]] [[Simon Cameron]], and later [[Edwin Stanton]], wanted control over the telegraph lines to maintain the flow of information. Early in the war, one of Stanton's first acts as Secretary of War was to move telegraph lines from ending at [[George B. McClellan|McClellan's]] headquarters to terminating at the War Department. Stanton himself said "[telegraphy] is my right arm". Telegraphy assisted Northern victories, including the [[Battle of Antietam]] (1862), the [[Battle of Chickamauga]] (1863), and [[Sherman's March to the Sea]] (1864).{{sfn|Hochfelder|2012}}

The telegraph system still had its flaws. The USMT, while the main source of telegraphers and cable, was still a civilian agency. Most operators were first hired by the telegraph companies and then contracted out to the War Department. This created tension between generals and their operators. One source of irritation was that USMT operators did not have to follow military authority. Usually they performed without hesitation, but they were not required to, so [[Albert J. Myer|Albert Myer]] created a [[Signal Corps (United States Army)|U.S. Army Signal Corps]] in February 1863. As the new head of the Signal Corps, Myer tried to get all telegraph and flag signaling under his command, and therefore subject to military discipline. After creating the Signal Corps, Myer pushed to further develop new telegraph systems. While the USMT relied primarily on civilian lines and operators, the Signal Corp's new field telegraph could be deployed and dismantled faster than USMT's system.{{sfn|Hochfelder|2012}}

===First World War===
During [[World War I]], Britain's telegraph communications were almost completely uninterrupted, while it was able to quickly cut Germany's cables worldwide.{{sfn|Kennedy|1971}} The British government censored telegraph cable companies in an effort to root out espionage and restrict financial transactions with Central Powers nations.<ref>{{Cite journal |last=Hills |first=Jill |date=June 2006 |title=What's New? War, Censorship and Global Transmission: From the Telegraph to the Internet |journal=International Communication Gazette |language=en |volume=68 |issue=3 |pages=195–216 |doi=10.1177/1748048506063761 |s2cid=153879238 |issn=1748-0485}}</ref> British access to transatlantic cables and its codebreaking expertise led to the [[Zimmermann Telegram]] incident that contributed to the [[American entry into World War I|US joining the war]].<ref>{{cite news |title=The telegram that brought America into the First World War |url=http://www.historyextra.com/article/bbc-history-magazine/telegram-brought-america-first-world-war |work=BBC History Magazin e |date=17 January 2017}}</ref> Despite British acquisition of German colonies and expansion into the Middle East, debt from the war led to Britain's control over telegraph cables to weaken while US control grew.<ref>{{Cite journal |last=Solymar |first=L. |date=March 2000 |title=The effect of the telegraph on law and order, war, diplomacy, and power politics |journal=Interdisciplinary Science Reviews |language=en |volume=25 |issue=3 |pages=203–210 |doi=10.1179/030801800679233 |bibcode=2000ISRv...25..203S |s2cid=144107714 |issn=0308-0188}}</ref>

===Second World War===
[[File:Lorenz SZ42.jpg|thumb|German Lorenz SZ42 teleprinter attachment (left) and Lorenz military teleprinter (right) at [[The National Museum of Computing]] on [[Bletchley Park]], England]]
[[World War II]] revived the 'cable war' of 1914–1918. In 1939, German-owned cables across the Atlantic were cut once again, and, in 1940, Italian cables to South America and Spain were cut in retaliation for Italian action against two of the five British cables linking Gibraltar and Malta. [[Electra House]], Cable & Wireless's head office and central cable station, was damaged by German bombing in 1941.

[[Resistance during World War II|Resistance movements]] in occupied Europe sabotaged communications facilities such as telegraph lines,<ref>{{Citation |title=World War II: German-occupied Europe |publisher=Encyclopaedia Britannica |url=https://www.britannica.com/event/World-War-II/German-occupied-Europe}}</ref> forcing the Germans to use [[wireless telegraphy]], which could then be [[Y-stations|intercepted]] by Britain.
The Germans developed a highly complex teleprinter attachment (German: ''Schlüssel-Zusatz'', "cipher attachment") that was used for enciphering telegrams, using the [[Lorenz cipher]], between German High Command ([[Oberkommando der Wehrmacht|OKW]]) and the army groups in the field. These contained situation reports, battle plans, and discussions of strategy and tactics. Britain intercepted these signals, diagnosed how the encrypting machine worked, and [[Cryptanalysis of the Lorenz cipher|decrypted]] a large amount of teleprinter traffic.{{sfn|Copeland|2006|pp=1–6}}