Why were the Normandy landings a success on and following 6 June 1944?

The invasion on D Day was successful. It led to the liberation of France & Western Europe & the defeat of Germany. The fact that the Allies had total naval freedom of action and air superiority was crucial. The planning that went into it was extensive and was in the main wholly effective. The deception plan which featured FUSAG (The mythical First US Army Group, nominally commanded by Patton) was believed to be effective in disinformation, many German High Commanders believed D Day was a feint to divert force from the Pas de Calais region. Strategic bombing delayed & indeed prevented Panzer forces deployment to the beacheads and to Normandy in general. Crucially the Allies took 2 ports, Mulberries, with them, pre cast concrete caissons which formed 2 harbours, one was subsequently destroyed in a storm. the landings of Airborne forces on the flanks, US in the West & British on the East of the 5 beaches was also very effective and proved their worth. Pluto, the Pipe Line Under The Ocean, delivered fuel direct to the beachead.