Today is the 75th Anniversary of the the Allied invasion of Normandy during World War II. It was the largest seaborne invasion in history, with more than 160,000 Allied troops landing along the 50-mile stretch of heavily-fortified French coastline, to fight Nazi Germany. Gen. Dwight D. Eisenhower called the operation a crusade in which, “we will accept nothing less than full victory.” More than 5,000 ships and 13,000 aircraft supported the D-Day invasion, and by day’s end, the Allies gained a foot-hold in Continental Europe. The cost in lives on D-Day was high. More than 9,000 Allied soldiers were killed or wounded, but their sacrifice allowed more than 100,000 soldiers to begin the slow, hard slog across Europe, to defeat Adolf Hitler’s crack troops.
What does the “D” in D-Day mean?
This is the most frequently asked question by visitors to The National WWII Museum. Many people think they know the answer: designated day, decision day, doomsday, or even death day. But the answer is not so simple. In Stephen Ambrose’s D-Day, June 6, 1944: The Climactic Battle of World War II, he writes:
Time magazine reported on June 12  that “as far as the U.S. Army can determine, the first use of D for Day, H for Hour was in Field Order No. 8, of the First Army, A.E.F., issued on Sept. 20, 1918, which read, ‘The First Army will attack at H-Hour on D-Day with the object of forcing the evacuation of the St. Mihiel salient.’” (p. 491)
In other words, the D in D-Day merely stands for Day. This coded designation was used for the day of any important invasion or military operation. For military planners (and later historians), the days before and after a D-Day were indicated using plus and minus signs: D-4 meant four days before a D-Day, while D+7 meant seven days after a D-Day.
In Paul Dickson’s War Slang, he quotes Robert Hendrickson’s Encyclopedia of Word and Phrase Origins:
Many explanations have been given for the meaning of D-Day, June 6, 1944, the day the Allies invaded Normandy from England during World War II. The Army has said that it is “simply an alliteration, as in H-Hour.” Others say the first D in the word also stands for “day,” the term a code designation. The French maintain the D means “disembarkation,” still others say “debarkation,” and the more poetic insist D-Day is short for “day of decision.” When someone wrote to General Eisenhower in 1964 asking for an explanation, his executive assistant Brigadier General Robert Schultz answered: “General Eisenhower asked me to respond to your letter. Be advised that any amphibious operation has a ‘departed date’; therefore the shortened term ‘D-Day’ is used.” (p.146) Brigadier General Schultz reminds us that the invasion of Normandy on June 6, 1944 was not the only D-Day of World War II. Every amphibious assault—including those in the Pacific, in North Africa, and in Sicily and Italy—had its own D-Day.
Want to learn more about D-Day?
D-Day, June 6, 1944 : the climactic battle of World War II by Stephen E. Ambrose. call number: D756.5.N6 A455 1994
The longest day : June 6, 1944 by Cornelius Ryan. call number: D756.5.N6 R9 1994
D-day [streaming media]. 45 minutes.
URL: Access for [Bloomington, Columbus, East, IUPUI, Kokomo, Northwest, South Bend, Southeast] – (Available on campus and off campus with authorized logon)