Sentence examples for D-day from inspiring English sources

The word "D-day" is correct and can be used in written English
"D-day" refers to the day on which a military operation began or is due to begin, typically a land invasion, and is typically used in reference to the Allied landings in Normandy, France in 1944, which marked the start of the liberation of Europe from Nazi Germany during World War II. For example, you could say "Today marks 75 years since D-Day, the largest seaborne invasion in history."