Soon after learning that his Division was to be used in the Invasion, Major-General Gale and members of his staff visited I Corps Headquarters in London to receive their orders. It was here that they worked out a plan which was scarcely altered in all the months thereafter.
Unfortunately it was impossible to transport all of the Division to Normandy in a single lift because 38 and 46 Groups simply did not have the capacity to achieve this. The plan, therefore, was for two lifts, the first of which was codenamed Operation Tonga, the second, Operation Mallard. Operation Tonga would take place during the early hours of D-Day, six hours before the sea-borne assault commenced, and it would bring the 3rd and 5th Parachute Brigades to Normandy, together with a relatively small number of gliders bringing in Divisional HQ and as many anti-tank guns as possible. Operation Mallard was set for the evening of D-Day, and it would deliver the balance of the Division's equipment and the glider-borne infantry of the 6th Airlanding Brigade.
The primary objective of the 6th Airborne Division was to capture the Ranville and Bénouville bridges, which in later years would become more famously known as the "Horsa" and "Pegasus" bridges. It was recognised that both bridges would very likely be wired and ready for demolition, and as soon as the Airborne landings were detected it had to be relied upon that it was only a matter of time before they were destroyed. The nearest DZ (drop zone) where major landings could take place was to the north of Ranville, over a mile to the east of the bridges. From here it would take several hours for the first troops to reach the bridges, a state of affairs that was not acceptable. The only alternative was a coup de main raid.
A coup de main involves a small force landing directly on top of objectives and seizing them with immense speed and surprise. Paratroopers were not suitable for such a role because the manner of their drop scatters them over a wide area and so it takes precious time for them to form up and be in a position to act as a unified and potent force. The assault could only be carried out by soldiers landing in gliders, each of which can carry a complete platoon, and therefore can deliver troops that are formed up and ready for action from the moment that they land.
The coup de main raid was to be carried out by "D" Company, reinforced by two platoons of "B" Company, of the 2nd Oxfordshire and Buckinghamshire Light Infantry, who were a part of the 6th Airlanding Brigade. These men, landing together with engineers, whose job was to clear demolition charges from the bridges, were to be the first British soldiers to land in France. The coup de main force, commanded by Major John Howard, was to fly in six Horsa gliders and land on two very small landing zones, each within a stones-throw distance of their respective bridges. Using the advantage of surprise, the men were then to pour out of their gliders, rout the German garrison, and then hold the bridges against counterattacks until the paratroopers arrived.
As the battle for the bridges was going on, pathfinders of the 22nd Independent Parachute Company, together with small advance parties of paratroopers, would simultaneously be deployed on DZ's K, N, and V. Their tasks were to lightly secure each of these zones and put their "Eureka" beacons in place to guide the main formation of aircraft, which would arrive half an hour later.
The 5th Parachute Brigade were to land on DZ-N, just north of Ranville, and then set up a defensive screen around the bridges. The 7th Battalion were to cross to the west of the River Orne and secure the villages of Bénouville and Le Port, whilst the 12th and 13th Battalions captured Ranville and a ridge to the south of it.
The 3rd Parachute Brigade was to be dropped on DZ's K and V. DZ-V, five miles to the east of Ranville, was assigned to the 1st Canadian and 9th Battalions. The latter were to silence the Merville Battery whilst the Canadians, amongst other tasks, were to protect engineers of the 3rd Parachute Squadron whilst they destroyed two bridges over the Rivers Divette and Dives at Varaville and Robehomme. The 8th Battalion were to land on DZ-K, four miles south of Ranville, from where they were similarly charged with escorting a detachment of engineers to the bridge at Troarn and a further two at Bures. With these objectives completed, the Brigade was then to fall back and hold the vital ridge that stretched from the Bois-de-Bavent woodland, four miles south-east of Ranville, up to the villages of Le Plein and Le Mesnil, two miles to the north and east of Ranville.
Several hours later, having given time for the paratroopers to move off their drop zones, gliders carrying Divisional HQ and all the anti-tank guns of the 4th Airlanding Anti-Tank Battery and one Troop from the 3rd, were to arrive at Ranville on LZ (Landing Zone) N, formerly DZ-N. This deployment would complete Operarion Tonga.
With the Division in place and holding the left flank of the invasion area, the sea-borne assault was to commence at dawn with the first British troops landing on the beaches at 07:30. It was hoped that by noon on D-Day, the Commandos of Lord Lovat's 1st Special Service Brigade would arrive at Bénouville and then cross the river into the Divisional perimeter. They were then to secure the northern sector of the ridge and clear the enemy from coastal strip in the area of Sallenelles and Franceville Plage.
On the evening of D-Day, Operation Mallard would take place and bring in the 6th Airlanding Brigade and most of the Division's equipment, including the light tanks of the 6th Airborne Armoured Reconnaissance Regiment and a Battery of artillery from the 53rd Light Regiment. Most of their gliders were to land on LZ-N at Ranville, but the remainder would be deposited on LZ-W, two miles to the north of Bénouville, an area which would be safely in the hands of I Corps by the time that they arrived. Despite the fact that the Division was to be flown in on two lifts, there were still not enough aircraft to bring in their full strength. The remainder would arrive on the second day of the invasion, crossing the English Channel by sea.
These supporting arms were to be distributed about the Divisional perimeter to wherever they were needed. The exact role of the 6th Airlanding Brigade, however, was to be defined by the situation on the ground as it presented itself, but the broad plan was for the Brigade to strengthen and enlarge the bridgehead southwards.
As the months wore on and D-Day drew closer, Intelligence were horrified to note that the Germans in the Ranville area were suddenly erecting metal stakes and tree trunks on every patch of open terrain where gliders or parachutists could conceivably be deployed. It was first feared that the Germans had discovered that the invasion was to come in Normandy, however a more detailed study concluded that these obstacles were being built all across France with no particular attention being paid to Normandy. Nevertheless these stakes, some of which were mined, presented a grave threat to the mass landing of gliders. It was decided, therefore, that the engineers of the 591st Parachute Squadron should accompany the first wave of paratroopers and then work feverishly with their explosives to clear the stakes from two landing strips, each 1,000 yards long by 60 yards wide, before the first gliders arrived.
Another worrying aspect was that the Germans were seen to be flooding large areas of open land in order to make them deadly to paratroopers. Some of these flooded areas were noted to be disturbingly close to DZ-V, where the majority of the 3rd Parachute Brigade was to land.