 As the boats approached to within a few hundred yards of the shore , they came under increasingly heavy fire from automatic weapons and artillery . The force discovered only then the ineffectiveness of the pre @-@ landing bombardment . Delayed by the weather and attempting to avoid the landing craft as they ran in , the bombers had dropped their ordnance too far inland , as a result of an order to wait 10 seconds extra before dropping their bombs . In the bombers , this translated to several miles inland , detonating some landmines that were planted by the Germans , but having no real effect on the coastal defenses . Another issue was the equipping of contact @-@ fuse bombs instead of time @-@ delay fuses in a tradeoff between more craters , meaning more cover for advancing infantry , or no craters , meaning easy vehicle access to the beach . 
