Answer: In other words, the D in D-Day merely stands for Day. This coded designation was used for the day of any important invasion or military operation. ... The National WWII Museum's exhibitions explore the history of the D-Day invasion of Normandy and the D-Day invasions in the Pacific.
The 'D' is derived from the word 'day'. 'D-Day' means the day on which a military operation begins. Some people think it is for "Doom" like doomsday or 'Destruction', but honestley its just means day
The American Civil War was a totally seperate issue to the Mexican War. Thats like equating the American War of Independence and saying that it was a direct cause for Vietnam.
