Why Is It Called D-Day?


On June 6, 1944, Allied forces invaded German-occupied beaches of Normandy, France. This significant day in history became commonly known as “D-Day,” though the actual meaning of the nickname isn’t as well understood.

Naming Theories

There are a few conjectures as to what the “D” stands for.Some have said it is an abbreviation for “departure” or “decision.” Others claim that it stands for “doomsday.” However, according to the United States military, the origin of the popular nickname has more to do with their terminology.

The Meaning of “D-Day”

The phrase “D-Day” was used by the Army to designate a specific starting date for field operations. Other phrases, like “D+2” would have referred to two days after the initial “D-Day.” This designation suggests that the letter “D” doesn’t stand for anything in particular outside of “Day”and that it served only as a point of reference.

Ships landing on D-Day

A similar term was used to refer to the designated hour on D-Day when the attack would begin. It was called “H-Hour” and “H-4” would have referred to four hours before the planned invasion.

Using this kind of shorthand military terminology dates back to recorded field orders in World War I, and an equivalent can be found in many countries. For example, you may have heard of “Zero Hour,” which is used by the British in conjunction with “Z-Day.” The term would be “Dan D” in Slovakia and “Lá L” in Ireland.

Do you have family who served in the military? Consider asking them about different military terms and stories and recording their responses in FamilySearch Memories. You might be surprised by what you discover!

About the Author