On the 70th anniversary of the Allied landings in Normandy ...
Lookups spiked on June 6, 2014.
Commemorations took place in France on the 70th anniversary of the Allied landings in Normandy.
D-day means "a day set for launching an operation; specifically : June 6, 1944, on which Allied forces began the invasion of France in World War II."
The term D-day, like the similar H hour, was used by the military to identify the appointed time that an operation would begin. Both terms were formed by using the initial letter of the word as an abbreviation. Since June 6, 1944, it has been most often used to refer to one of the largest military operations ever launched, one that marked the beginning of the end of World War II.