2455: H-Hour & D-Day Sep 1, 2021

H-Hour refers to the time of day which a battle was set to commence, with this phrase entering the military parlance of the First World War. The 'H-' stands for 'hour' in effect, but the Norwegian calque 'klokken H' only took the letter and not the pattern. This pattern was also used for D-Day, which now refers to a specific moment in history—June 6, 1944—but just referred to the planned, secretive date of the Normandy landings.