Doomsday? Decision Day? Death Day?

The invasion of Normandy, France in 1944 or D-Day as it鈥檚 commonly called is considered to be one of the most pivotal battles in the Second World War responsible for turning the tide in the Allies鈥 favour before the eventual defeat of Nazi Germany, but some Canadians may still be unfamiliar with where the 鈥淒鈥 in D-Day came from and how the term originated.

, the 鈥淒鈥 in D-Day was used to indicate the day on which a combat attack or operation was to be initiated. The 鈥淒鈥 itself is simply an alliterative placeholder for the word day, which makes D-Day a somewhat redundant term.

The military also used the phrase 鈥淗-Hour鈥 to refer to the time of day when the operation would begin.

Large-scale operations like the Normandy invasion in France took months to plan, which meant that commanders had to be careful about writing down specific dates that could fall into enemy hands. That鈥檚 why military units relied on placeholders such as D-Day in correspondence concerning plans for the attack.

In order to track the passage of time, the military would use a system of pluses and minuses to mark the days before and after the operation launch date and time.

For example, the day before the attack date would be called D-1, two days after the day would be D+2, and three hours before the start time would be called H-3. By this system, the actual day of the operation was simply called D or D-Day.

When it came closer to the time of the assault, the U.S. Army Centre said military planners would put out an order with the actual date and times for the operation.

The use of D-Day is not exclusive to the famed Normandy landings on June 6, 1944 in the Second World War. In fact, the U.S. Army Centre traced the term back to the First World War when the American Expeditionary Forces used it in a communication dated Sept. 7, 1918.

鈥淭he First Army will attack at H hour on D day with the object of forcing the evacuation of the St. Mihiel Salient,鈥 the memo stated.

Although D-Day has been used to plan many military operations, it鈥檚 most commonly associated with the Normandy invasion, in which nearly 150,000 Allied troops landed in France, including 14,000 Canadians at Juno Beach.

On that day alone, it鈥檚 estimated that more than 4,000 Allied forces lost their lives, including 381 Canadian soldiers and airmen who died.

D-Day and the greater Battle of Normandy, which lasted from June 6, 1944 to Aug. 21, 1944, are credited with paving the way for the eventual liberation of Western Europe from Nazi occupation.

June 6, 2019 will mark the 75th anniversary of D-Day and the Battle of Normandy.