Letters, Jun. 12, 1944

DDay, H-Hour

Sirs:

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.

So...

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