A 60th Anniversary

Uncle Tommy landed at Normandy the morning of June 6th, 1944. More than 2,000 GIs died on the beaches that morning - more than 10,000 on D-Day. For the next 50+ years, Uncle Tommy would go to his unit’s reunions, driving all over the U.S. to do so. He once admitted that basically everyone told the same stories every year - which seemed to get more and more embellished – yet, there was something special about just getting together. In a few weeks I’m going to see Uncle Tommy once more. Like many WWII vets, it is comfortable for him to talk to old war buddies about their shared experiences, but next to impossible to talk to family about them.

And, so that you can settle all those arguments you had over the weekend about the definition of D-Day, it’s actually pretty simple:

The term D-Day is used generically by the military to simply mean the day on which a combat attack or operation is to be initiated, but it is often used to refer to the Battle of Normandy of June 6, 1944, which marked the commencement of the liberation of mainland Europe from German occupation during World War II.

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. The letters are derived from the words for which they stand, "D" for the day of the invasion and "H" for the hour operations actually begin. There is but one D-day and one H-hour for all units participating in a given operation. It is unnecessary to state that H-hour is on D-day.

When used in combination with figures and plus or minus signs, these terms indicate the length 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. H+75 minutes means 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 or days, hours, or minutes. At the appropriate time, a subsequent order is issued that states the actual day and times.

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 September 7, 1918: "The First Army will attack at H hour on D day with the object of forcing the evacuation of the St. Mihiel Salient."

(In French, it is called jour-J.)