Crete's mountainous terrain offers comparatively few places where transport aircraft can land and take off. Earthworks alone would not defeat every paratrooper. Their purpose was to deny the landing surfaces needed to bring in mountain troops, equipment, and supplies. Ploughed ground, obstacles, and booby traps could impose that denial even without a large stock of mines. The lost opportunity was practical combat engineering and access denial.
Chapter · 45:33-47:47
Spade work could deny the German air bridge
Obstructing riverbeds, airfields, and improvised landing grounds could have denied the German transport force the infrastructure it needed.