Questions that can be answered by this FAQ:
Q: What is the origin of the 21-gun salute?
A: Gun salutes are not a recent tradition. As early as the 14th century, cannons were fired on military occasions to demonstrate peaceful intentions. We know that warships later started firing 7-gun salutes (possibly because of the astrological/Biblical connotations of the number, although no one knows for sure.) The history of how this finally morphed into a 21-gun salute that is still used today is equally vague, and involves theories about the increased supplies of gunpowder and the ancient significance of the number 3. You can read more about this topic on the following pages:
Q: What does the "D" in D-Day stand for?
A: As odd as it sounds, the "D" in D-Day is merely meant to designate the "day" of the invasion. It is used in combat operations where the day needs to be secret (as in the most famous D-Day, the invasion of Normandy on June 6, 1944) or when the day has not yet been determined. For more information, visit the U.S. Army Center of Military History’s FAQ, What does the "D" signify in D-Day, and the "H" signify in H-Hour?. (http://www.history.army.mil/faq/ddaydef.htm)
Q: How far is a klick?
A: In many military-related movies and television shows, characters describe distances in terms of "klicks", causing many people to wonder what a "klick" (also sometimes spelled "click", "klik", or "clic") is. This term is shorthand/slang for a "kilometer". We found its definition in several on-line glossaries, including this Glossary of Words used by CAP Marines in Vietnam (http://www.capmarine.com/cap/glossary.htm) and this Language of War page from the PBS web site for their "Vietnam Online" program. (http://www.pbs.org/wgbh/amex/vietnam/refer/language.html) Finally, it is also worth noting that the book War Slang by Paul Dickson (London: Pocket Books, 1994) indicates that "klick" originated in the Vietnam war, and also gives a second definition as "a short distance."