Editing Traffic analysis (section)

===World War II===
* In the early part of [[World War II]], the [[aircraft carrier]] {{HMS|Glorious}} was evacuating pilots and planes from [[Norway]]. Traffic analysis produced indications {{ship|German battleship|Scharnhorst||2}} and {{ship|German battleship|Gneisenau||2}} were moving into the [[North Sea]], but the Admiralty dismissed the report as unproven. The captain of ''Glorious'' did not keep sufficient lookout and was subsequently surprised and sunk. [[Harry Hinsley]], the young [[Bletchley Park]] liaison to the Admiralty, later said that his reports from the traffic analysts were taken much more seriously thereafter.<ref>{{cite web
 |url         = http://www.warship.org/no11994.htm
 |title       = The Loss of HMS Glorious: An Analysis of the Action
 |author      = Howland, Vernon W.
 |date        = 2007-10-01
 |access-date  = 2007-11-26
 |url-status     = dead
 |archive-url  = https://web.archive.org/web/20010522092000/http://www.warship.org/no11994.htm
 |archive-date = 2001-05-22
}}</ref>
* During the planning and rehearsal for the [[attack on Pearl Harbor]], very little traffic was passed by radio, subject to interception. The ships, units, and commands involved were all in Japan and in touch by phone, courier, signal lamp, or even flag. None of that traffic was intercepted, and could not be analyzed.<ref name="Kahn"/>
* The espionage effort against Pearl Harbor before December did not send an unusual number of messages; Japanese vessels regularly called in Hawaii and messages were carried aboard by consular personnel. At least one such vessel carried some Japanese Navy Intelligence officers. Such messages could not be analyzed. It has been suggested,<ref>{{cite book
 | author = Costello, John
 | title = Days of Infamy: Macarthur, Roosevelt, Churchill-The Shocking Truth Revealed : How Their Secret Deals and Strategic Blunders Caused Disasters at Pear Harbor and the Philippines
 | publisher = Pocket
 | year = 1995
 | isbn = 0-671-76986-3
 | url-access = registration
 | url = https://archive.org/details/daysofinfamymaca0000cost
 }}</ref> however, the volume of diplomatic traffic to and from certain [[consular office|consular stations]] might have indicated places of interest to Japan, which might thus have suggested locations to concentrate traffic analysis and decryption efforts.{{Citation needed|date=November 2007}}
* [[Nagumo Chuichi|Admiral Nagumo]]'s Pearl Harbor Attack Force sailed under radio silence, with its radios physically locked down. It is unclear if that deceived the US since Pacific Fleet intelligence had been unable to locate the Japanese carriers in the days immediately preceding the [[attack on Pearl Harbor]].<ref name="Kahn"/>
* The [[Imperial Japanese Navy|Japanese Navy]] played radio games to inhibit traffic analysis (see Examples, below) with the attack force after it sailed in late November. Radio operators normally assigned to carriers, with a characteristic Morse Code "[[Telegraph key#"Fist"|fist]]", transmitted from inland Japanese waters, suggesting the carriers were still near Japan.<ref name="Kahn"/><ref>{{cite book
 | title =  "And I Was There": Pearl Harbor And Midway -- Breaking the Secrets.
 | url =  https://archive.org/details/andiwastherepear00layt
 | url-access =  registration
 | author = Layton, Edwin T.
 |author2=Roger Pineau, John Costello
 | publisher = William Morrow & Co
 | year = 1985
 | isbn  =0-688-04883-8
}}</ref>
* [[Operation Quicksilver (WWII)|Operation Quicksilver]], part of the British deception plan for the [[Invasion of Normandy]] during World War II fed German intelligence a combination of true and false information about troop deployments in Britain, which caused the Germans to deduce an order of battle that suggested an invasion at the [[Pas-de-Calais]], instead of Normandy. The fictitious divisions that were created for the deception were supplied with real radio units, which maintained a flow of messages that was consistent with the deception.<ref>{{cite book |last=Masterman |first=John C |author-link=John Cecil Masterman |title=The Double-Cross System in the War of 1939 to 1945 |publisher=Australian National University Press |isbn=978-0-7081-0459-0 |year=1972 |orig-year=1945|page=233 }}</ref>