 With the initial targets <unk> , the second and larger wave of assault landings brought in reinforcements , support weapons and headquarter elements at 07 : 00 to face nearly the same difficulties as had the first . The second wave was larger , and so the defenders ' fire was less concentrated . The survivors of the first wave were unable to provide effective covering fire , and in places the fresh landing troops suffered casualty rates as high as those of the first wave . Failure to clear paths through the beach obstacles also added to the difficulties of the second wave . In addition , the incoming tide was beginning to hide the remaining obstacles , causing high attrition among the landing craft before they had reached the shore . As in the initial landings , difficult navigation caused disruptive <unk> , scattering the infantry and separating vital headquarters elements from their units . 
