As almost 5,000 ships approached the beaches, 9,000 airplanes filled the sky, "almost wing tip to wing tip." The aerial bombing was done by Lancasters, Fortresses and Liberators up high, B-26s just lower, and on the deck, cover was provided by Spitfires, Mustangs and Thunderbolts, which whistled over the head of the seasick troops praying below. Just minutes prior to the landing of amphibious forces one of the sad consequences of the cloud layer played an important role in the invasion. Maneuvering mostly by dead reckoning, bomber pilots were loathe to unleash their bombs too soon, for fear of killing their own men at sea lying off the coastline or the paratroopers just inland. As a result most bombs fell harmlessly behind the German fortifications. In fact, at the beginning of the assault, most major German installations were still untouched. This accounted for much of the bloodshed on the beaches, especially Omaha.