D-Day (military term): Difference between revisions

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The earliest use of these terms by the [[United States Army|U.S. Army]] that the Center of Military History has been able to find was during [[World War I]]. In Field Order Number 9, First Army, [[American Expeditionary Force]]s, dated 7 September 1918: "The First Army will attack at H hour on D day with the object of forcing the evacuation of the [[Battle of Saint-Mihiel|St. Mihiel Salient]]."
 
The earliest use of these terms by the [[United States Army|U.S. Army]] that the Center of Military History has been able to find was during [[World War I]]. In Field Order Number 9, First Army, [[American Expeditionary Force]]s, dated 7 September 1918: "The First Army will attack at H hour on D day with the object of forcing the evacuation of the [[Battle of Saint-Mihiel|St. Mihiel Salient]]."
   
D-Day for the invasion of Normandy by the Allies was originally set for June 5, 1944, but bad weather and heavy seas caused [[Dwight D. Eisenhower|Gen. Dwight D Eisenhower]] to delay until June 6 and ''that'' date has been popularly referred to ever since by the short title "D-Day". Because of the connotation with the invasion of Normandy, planners of later military operations sometimes avoided the term to prevent confusion. For example, [[Douglas MacArthur]]'s [[Battle of Leyte|invasion of Leyte]] began on "A-Day", and the [[Battle of Okinawa|invasion of Okinawa]] began on "L-Day". The Allies proposed [[Operation Downfall|invasions of Japan]] that would have begun on "X-Day" (on [[Kyūshū]], scheduled for November 1945) and "Y-Day" (on [[Honshū]], scheduled for March 1946).
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D-Day for the invasion of Normandy by the Allies was originally set for June 5, 1944, but bad weather and heavy seas caused [[Dwight D. Eisenhower|Gen. Dwight D Eisenhower]] to delay until June 6 and ''that'' date has been popularly referred to ever since by the short title "D-Day". Because of the connotation with the invasion of Normandy, planners of later military operations sometimes avoided the term to prevent confusion. For example, [[Douglas MacArthur]]'s [[Battle of Leyte|invasion of Leyte]] began on "A-Day", and the [[Battle of Okinawa|invasion of Okinawa]] began on "L-Day". The Allies proposed [[Operation Downfall|invasions of Japan]] that would have begun on "X-Day" (on [[Kyūshū]], scheduled for November 1945) and "Y-Day" (on [[Honshū]], scheduled for March 1946). THE AMARICANS ATTACKED AND THEY ALL LIVED HAPPILY EVER AFTER
   
 
==Notes==
 
==Notes==

Revision as of 00:36, 12 January 2010

Battle plans for the Normandy Invasion, the most famous D-Day.

D-Day is a term often used in military parlance to denote the day on which a combat attack or operation is to be initiated. "D-Day" often represents a variable, designating the day upon which some significant event will occur or has occurred; see Military designation of days and hours for similar terms. The initial D in D-Day has had various meanings in the past, while more recently it has obtained the connotation of "Day" itself, thereby creating the phrase "Day-Day", or "Day of Days".[1] On the same principle, the equivalent terms in French, Basque, Romanian and Slovenian are Jour J, E eguna, Ziua-Z and Dan D.[citation needed]

The best known D-Day is June 6, 1944 — the day of the Normandy Landings— initiating the Western Allied effort to liberate mainland Europe from Nazi occupation during World War II. However, many other invasions and operations had a designated D-Day, both before and after that operation.[2]

The terms D-Day and H-Hour are used for the day and hour on which a combat attack or operation is to be initiated. They designate the day and hour of the operation when the day and hour have not yet been determined, or where secrecy is essential. For a given operation, the same D-Day and H-Hour apply for all units participating in it.

When used in combination with numbers, and plus or minus signs, these terms indicate the point of time preceding or following a specific action. Thus, H−3 means 3 hours before H-Hour, and D+3 means 3 days after D-Day. (By extension, H+75 minutes is used for H-Hour plus 1 hour and 15 minutes.)

Planning papers for large-scale operations are made up in detail long before specific dates are set. Thus, orders are issued for the various steps to be carried out on the D-Day or H-Hour minus or plus a certain number of days, hours, or minutes. At the appropriate time, a subsequent order is issued that states the actual day and times.

In spacecraft launchings, NASA utilizes the term 'T-Time' for the timing of the launch sequence down to the second (rather than M-Minute and S-Second), as in the expression "T minus 10 seconds and counting" for their countdown clock.

When referencing a local time zone, "Z-8" ("zulu minus eight") refers to Universal Co-ordinated Time (formerly Greenwich Mean Time) minus 8 hours, or 8 hours behind UTC. "Z+10" means 10 hours ahead of or earlier than UTC. This is because the time zone at zero degrees longitude is designated by the letter Z, which is phonetically designated as 'zulu', there being 24 principal time zones world wide, each designated by a distinct letter of the roman alphabet. Thus, for example, Vancouver Canada local time is 1 o'clock in the morning when it is 9 o'clock in London UK, since Pacific Standard Time is Z-8 (9-8 = 1 in this example).

History

Official U.S. Twelfth Army situation map for 2400 hours, 6 June 1944.

The earliest use of these terms by the U.S. Army that the Center of Military History has been able to find was during World War I. In Field Order Number 9, First Army, American Expeditionary Forces, dated 7 September 1918: "The First Army will attack at H hour on D day with the object of forcing the evacuation of the St. Mihiel Salient."

D-Day for the invasion of Normandy by the Allies was originally set for June 5, 1944, but bad weather and heavy seas caused Gen. Dwight D Eisenhower to delay until June 6 and that date has been popularly referred to ever since by the short title "D-Day". Because of the connotation with the invasion of Normandy, planners of later military operations sometimes avoided the term to prevent confusion. For example, Douglas MacArthur's invasion of Leyte began on "A-Day", and the invasion of Okinawa began on "L-Day". The Allies proposed invasions of Japan that would have begun on "X-Day" (on Kyūshū, scheduled for November 1945) and "Y-Day" (on Honshū, scheduled for March 1946). THE AMARICANS ATTACKED AND THEY ALL LIVED HAPPILY EVER AFTER

Notes

  1. ^ "D-Day". The Oxford Companion to World War II. Oxford: Oxford University Press. 2005. p. 220. ISBN 0-19-280666-1. 
  2. ^ Hakim, Joy (1995). A History of Us: War, Peace and all that Jazz. New York: Oxford University Press. ISBN 0-19-509514-6. 

External links