Everybody refers to DDay, H-Hour. Can you please tell me what they stand for or how they originated?
(NAME WITHHELD BY REQUEST) Toronto
¶ D for Day, H for Hour means the undetermined (or secret) day and hour for the start of a military operation. Their use permits the entire timetable for the operation to be scheduled in detail and its various steps prepared by subordinate commanders long before a definite day and time for the attack have been set. When the day and time are fixed, subordinates are so informed.