What had the Allies done to interrupt German defese of Normandy?

Answer 1

They had landed directly on enemy controlled beaches about 200 miles southeast from where the Germans were expecting them. -Even after the invasion started, the German high Command were convinced it would happen at Calais.

Answer 2

Im not an expert, but i beleive that there was a whole bunch of tactical deception on dday. we (allies) had a fake army north of where we launched from (dont know the name). we had inflatable tanks, jeeps, planes, and troop transports. this was greatly reinforced by the fact that general patton visited the camp occasionally (he was a major tank commander). where we had the ficticious army, we were at the narrowest point in the english channel so that was the ideal place to launch an assault. normandy was almost twice as far to cross. the german commander came just in time and decided to reinforce the german deffenses by adding more bunkers, antitank landmines and barricades, and a pile of telephone poles, made to look like an artilery gun that was 20 miles away from the beach but could rain accurate fire on it. we sent in our most elite fighting group to go disable the gun but when they got there and realized that there was no threat, they headed back and were ambushed on their way back ( i dont believe it was a masacre, but it was a decent ambush). another deception we used was an attempt at an amphibious tank. we had tanks with propellers put on them and that had a 10 ft tall canvas wall on all sides, it was design to not look like a tank untill it was on the beach, then the canvas would be dropped and the main turret could start firing. since we have never used anything like this, the germans wouldnt realize the threat until the canvas was dropped...if the canvas ever got dropped. since it was only canvas 13 out of the 14 that were launch sank (not sure on the total number lost, i know it was low and only 1 made it). the one that did make it was destroyed by a landmine almost immediatly.

hope this helps