The following article on H-Hour is an excerpt from Barrett Tillman' D-Day Encyclopedia.
The term"H-hour"reportedly originated in World War I, but details are lost in the mists of time. On 6 June 1944 H-hour was 0630 on most beaches, one hour after first light, an hour after low tide.
H-hour was the name given to the airborne assault that kicked off Operation Overlord, the Normandy landings of World War Two. Units involved in H-hour included the U.S. 101st Airborne Division and the U.S. 82nd Airborne Division. Among non-American units involved were the British 6th Airborne Division.
These airborne assaults occurred three hours before the main beach landings and amphibious assault on the shores of Normandy. The airborne invasion consisted of more than 20,000 men and 1,200 planes and gliders. With all the confusion created among German lines, the beach landings were able to occur with greater easer.
The choice was essentially a compromise. Landing at"dead low tide"would avoid most of the beach obstacles that threatened landing craft but would expose the Allied troops to a long advance over open beaches swept by machine guns and mortar fire. Landing at high tide would play to the strength of the defenses, as the obstacles (See Atlantic Wall) would then be most effective against the Higgins Boats, though assault troops would have less beach to cover once they reached shore. The compromise was to land on a rising tide.
This article is part of our larger selection of posts about the Normandy Invasion. To learn more, click here for our comprehensive guide to D-Day.