The highly trained 4th Division faced a mediocre German unit composed of conscripts; all the best troops of the 709th Division had been sent to the Eastern Front. The Allies achieved and maintained air superiority, which meant that the Germans were unable to make observations of preparations underway in Britain prior to the invasion and were unable to launch airborne counterassaults on D-Day. Extensive Allied reconnaissance provided the attackers with detailed maps of the defenses and terrain. Unlike neighboring Omaha, the preliminary aerial bombardment was highly effective at Utah. Indecisiveness and an overcomplicated command structure on the part of the German high command was also a factor in the Allied success at Utah and throughout the Normandy campaign.