D-Day:  Three unique perspectives.
 
What does D-day mean?

D-Day is a military term. The D stands for the day an operation or attack is to start. The H in H-Hour stands for the hour that the operation or attack is to start. If you see a + or – sign after and H or a D it tells you what time it is before (–) or after (+) combat has started.

D+4 means 4 days after D-Day
D-7 means 7 days before D-Day
H+15 means 15 minutes after H-Hour
H-25 means 25 minutes before H-Hour


Overturned tank at Normandy.


Leaping for cover during the Normandy invasion.

The term first appeared in WWI in the records of the American Expeditionary Force in the planning for the attack of the St. Mihiel Salient, September 7, 1918. The St. Mihiel Salient was where American tanks were first lead into battle by George Patton on September 12, 1918.

The term D-Day has become associated with the invasion of Normandy, but in World War II, D-Day was experienced regularly by troops in both the Pacific or European Theater of operations.


Allied ships landing at Normandy.

Resources
Web movies about D-day

Center for Military History

The meaning of the word D-Day (PDF)

Eisenhower’s D-Day Address

The United States Army D-day site  

Utah Beach to Cherbourg by Maj. Roland G. Ruppenthal

Cross Channel Attack by Gordon A. Harrison