It can include opening, reading and total or selective obliteration of letters and their contents, as well as covers, postcards, parcels and other postal packets.
[citation needed] Prisoner-of-war and internee mail is also subject to postal censorship, which is permitted under Articles 70 and 71 of the Third Geneva Convention (1929–1949).
Until recent years, the monopoly for carrying civilian mails has usually been vested in governments,[3][4] and that has facilitated their control of postal censorship.
Censored mail can usually be identified by various postmarks, dates, postage stamps and other markings found on the front and reverse side of the cover (envelope).
The number of Union and Confederate soldiers in prisoner of war camps would reach an astonishing one and a half million men.
[13] In 1782 responsibility for administering the Secret Office was transferred to the Foreign Secretary and it was finally abolished by Lord Palmerston in 1847.
[14] Initially offices were in Pretoria and Durban and later throughout much of the Cape Colony as well a POW censorship[15] with camps in Bloemfontein, St Helena, Ceylon, India and Bermuda.
[16] The British Post Office Act 1908 allowed censorship upon issue of warrants by a secretary of state in both Great Britain and in the Channel Islands.
[19] Postal control was eventually introduced in all of the armies, to find the disclosure of military secrets and test the morale of soldiers.
[19] American censors would only open mail related to Spain, Latin America or Asia—as their British allies were handling other countries.
[20] Those writing postcards in the field knew they were being censored, and deliberately held back controversial content and personal matters.
[19] For example, German censors prevented postcards with hostile slogans such as "Jeder Stoß ein Franzos" ("Every hit a Frenchman") among others.
[22]: 126–139 The Irish Civil War saw mail raided by the IRA that was marked as censored and sometimes opened in the newly independent state.
[27]: 2 British censorship was primarily based in the Littlewoods football pools building in Liverpool with nearly 20 other censor stations around the country.
[29] Additionally the British censored colonial and dominion mail at censor stations in the following places: In the United States censorship was under the control of the Office of Censorship whose staff count rose to 14,462 by February 1943 in the censor stations they opened in New York, Miami, New Orleans, San Antonio, Laredo, Brownsville, El Paso, Nogales, Los Angeles, San Francisco, Seattle, Chicago, San Juan, Charlotte Amalie, Balboa, Cristóbal, David, Panama, Honolulu, Pago Pago and Washington, D.C.[31]: 25–27 The United States blacklist, known as U.S. Censorship Watch List, contained 16,117 names.