Some sources claim that the D stands for Deliverance; others that it stands for Day.
In the words of Mike Wagstaffe, the inimitable webmaster and erstwhile questions guru of Stockport Quiz League: "according to most reputable sources the 'D' in 'D–Day' is derived from the word 'day', but doesn't actually stand for anything. 'D' is used as a point of reference for all dates related to an operation, so the day before is 'D minus one' and the day after is 'D plus one' etc.
"Other, less reliable sources peddle the (completely incorrect) idea that the 'D' stands for 'Deliverance'."
© Haydn Thompson 2021