 On Rommel's order, the number of mines along the coast was tripled.Given the Allied air supremacy (4,029 Allied aircraft assigned to operations in Normandy plus 5,514 aircraft assigned to bombing and defence, versus 570 Luftwaffe planes stationed in France and the Low Countries), booby-trapped stakes known as "Rommelspargel" (Rommel's asparagus) were set up in meadows and fields to deter airborne landings.Rommel, believing that the Germans' best chance was to stop the invasion at the shore, requested that mobile reserves—especially tanks—be stationed as close to the coast as possible.