h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Why is D-Day called D-Day ?

Anybody know

"D-Day" is a military term designating the start date for launching an operation, but in modern history it generally refers to the events of June 6th 1944. "Overlord" is the official Normandy operation name.

-from www.ddaymuseum.org

I hope that answers your question.

Not really, I know what D-day was but not why it was called D-Day

But thanks for replying anyway

The D stands for the Day of the attack. On the 4th of june it would have been D-2,on the 5th it would be D-1 and on the 6th it was D day.

H-Hour = The launch Hour for an operation
D-Day = The launch DAY for an operation
M-Month = Guess
Y-Year = I am not joking.

This is done to make sure that everyone involved know the pertinant time frame. D-Day signifies that a particular day is imprtant, while Y-Year signifies a particular year is important. Somewhat simple minded, but it works.

Why do we say T-10,9,8...?
What does "T" stand for here?

It could stand for Takeoff, or maybe time.

That could be right - in flying there's a T1 and a T2 (if memory serves, which it often doesn't these dayes ) whereby T1 is when the aircraft can be rotated (nose up) and T2 is when the rear wheels leave the ground.
...Not that this helps