One thing that the Germans got wrong about D-Day was the timing. They were expecting the invasion to come when there was a high tide at dawn. The actual plan was to attack on a rising tide. That, combined with the weather, led to the Germans being caught by surprise. June 6 was not a good day for the invasion, so the Germans relaxed a little. Most of the generals were not even with their units. Many were at a map exercise. Others detoured through Paris on the way to the exercise. Rommel went to his wife’s birthday party on the way to beg Hitler for more troops. If Trump knows D-Day history, he will do something similar. Go against what the derps expect and take action when they have let their guard down a little bit.
Another bit touched on by others is the Ghost Army. The importance of that was to keep the Germans believing that Normandy was a diversion, and that the main attack would come at Calais with over twenty divisions. That diversion kept the best German divisions, as well as most of the Panzers, immobilized. Most of the German Fifteenth Army did not see action until Market-Garden in September(but that is another story). The relevant point here is to keep the enemy fixated on what they see as a greater threat while hitting them and advancing your plan somewhere else.
That is a good point. We expect the attack to come from the FBI. Personally I never did they’re far to corrupted. Which means Wray in Patton’s position to distract. Another agency might run the operations if it takes place at all.