The Allied planners of Operation Overlord feared their seaborne troops would get trapped on the beaches. At the western end of the landing zone, the Germans had flooded the coastal meadows: the only route inland was via four raised causeways. At the eastern end, troops could advance only if they controlled two key bridges over the River Orne and Caen Canal.
The Allied plan was to capture these bridges, at Bénouville and Ranville, and destroy five others. Shortly after midnight, 181 British troops from the 6th Airborne Division were to land by glider and seize the bridges: a further 7,000 troops would land by parachute and destroy the remainder.
Simultaneously with the British operation, 13,000 American paratroopers were to be dropped at the landing zone’s western end. Their task was to capture the raised causeways and the town of Sainte-Mère-Église.
The role of the French resistance was to blow bridges, viaducts and railway junctions – anything that would prevent the Germans from moving reinforcements towards the coast.
Field Marshal Rommel’s strategy was the exact reverse of the Allied one: he intended to trap the Allied forces inside their beachhead by thrusting his armoured panzers northwards to the coast. But the German advance was contingent on controlling bridges, causeways and Sainte-Mère-Église. If Rommel lost the latter, he would also have lost the main highway to Cherbourg.