DAY D derived from the crucial D-Day of the start of the Allied landing on the beaches of Normandy, the beginning of the counter-offensive and the final defeat of the Nazis. A critical moment is called in a program, project, campaign, or action plan, on which overall success or failure depends.
In military jargon is the day a combat operation is started or started. But D-Day by antonomasia was the day when the early morning landing of Normandy in World War II began, on Tuesday, June 6, 1944, the day that the French call Jour J or le Choc. The agreed day had been 5, but bad weather and sea conditions in the English Channel advised to do so the next day. It began with the Overlord operation followed by the Neptune operation.
