The evolution of the final invasion fleet illustrates the problems the Germans had in balancing naval practicality with the needs of a land army capable of achieving its assigned tasks. The planned landing areas were three separate zones, for the coastline is one of cliffs with three limited entry points. In the east, Cuckmerehaven is a narrow river valley, very flat near the sea and narrowing inland, the River Cuckmere running from the north through a cutting in the South Downs. The Cuckmerehaven landing was carried out by sixth Mountain Division, supported by the tank company. The defences map suggested that the fortifications were modest. The Mountain Divisions objective was the open country north of the Downs, past Alfriston, to protect the flank of the 26 Infantry coming west from Polegate and later to guarantee this flank to allow the passage of the Panzers due in the second wave.