 Pas de Calais, the closest point in continental Europe to Britain, was the location of launch sites for V-1 and V-2 rockets, then still under development.The Germans regarded it as the most likely initial landing zone, and accordingly made it the most heavily fortified region.It offered the Allies few opportunities for expansion, however, as the area is bounded by numerous rivers and canals, whereas landings on a broad front in Normandy would permit simultaneous threats against the port of Cherbourg, coastal ports further west in Brittany, and an overland attack towards Paris and eventually into Germany.