The paratroopers and glider-borne airborne troops of the division, commanded by Major-General Richard Nelson Gale, landed on the eastern flank of the invasion area, near to the city of Caen, tasked with a number of objectives.

A small force of glider-borne troops, from the 2nd Battalion Oxfordshire and Buckinghamshire Light Infantry, secured two bridges over the Caen Canal and River Orne in a coup de main operation.

A bridgehead was formed by the division, and it successfully repulsed a number of German counter-attacks until Allied ground forces from the invasion beaches reached its positions.

The actions of the division severely limited the ability of the German defenders to communicate and organise themselves, ensuring that the seaborne troops could not be attacked during the vital first few hours after landing when they were most vulnerable.

[5] "Plan C", an ambitious proposal put forward by General George C. Marshall, the Chief of Staff of the United States Army, would have involved a large airborne drop on the River Seine, aiming to cut the German forces in half during D-Day itself.

[8] The final plan would utilise three divisions in the first assault, with airborne forces being dropped onto the town of Caen early on the first day to seize the first breakout route.

[13] As late as January 1944, Gale noted that he had "no indication as yet of a definite airborne task" for his unit and continued to keep all options open,[14] reflecting the ongoing discussions at the strategic level over the wider plan for D-Day.

[16] The division was allotted three specific tasks to achieve as a part of Tonga, apart from protecting the eastern flank of the Allied seaborne landings and taking control of the areas of strategic importance to the east of Caen.

Second, the division was to destroy the heavily fortified Merville coastal artillery battery located at Franceville Plage, to ensure that it could not shell the British forces landing in the area codenamed Sword.

[16] Detailed planning for Tonga began in February, starting with the number of transport aircraft assigned to the operation being expanded rapidly to accommodate the entire division.

Glider units spent hours aloft every day circling over airfields as they practiced the manoeuvers required to land the airborne forces next to the bridges over the Orne River, the Caen canal, the Dives, and the Merville battery.

In the landing grounds used by the division for their operations, dozens of poles similar to those in Normandy were erected, with engineering units then timed on how fast they could demolish the obstacles.

[18] The battalion assigned to neutralising Merville spent two weeks at a special camp, where they built a replica of the battery and carried out several rehearsal exercises in and around it.

A coloured film was produced from aerial reconnaissance photographs which, when played at the correct speed and height over the scale models, realistically simulated the paths the glider pilots would take towards their landing-zones.

[30] Operation Tonga began at 22:56 on the night of 5 June, when six Handley Page Halifax heavy bombers took off from RAF Tarrant Rushton towing six Horsa gliders carrying the coup-de-main force; this consisted of D Company, 2nd Battalion Oxfordshire and Buckinghamshire Light Infantry (part of the 6th Airlanding Brigade, but attached to the 5th Parachute Brigade for the initial invasion) reinforced with two extra platoons from B Company and a party of Royal Engineer sappers under the overall command of Major John Howard, who were tasked with capturing the bridges over the Caen Canal and the River Orne.

[31] A few minutes later, between 23:00 and 23:20, six Armstrong Whitworth Albemarle transports took off carrying pathfinders of the 22nd Independent Parachute Company, who were to mark the three drop-zones to be used by the airborne troops of the division.

The first consisted of 239 Douglas Dakota and Short Stirling transports as well as seventeen Horsa gliders, carrying the bulk of the 3rd and 5th Parachute Brigades and their heavy equipment.

[38] While the force waited for the rest of the division to land, and for the 7th Parachute Battalion to arrive to reinforce their position, they had to repel several spontaneous attempts by the Germans to re-take the bridges.

The first organised German responses to the capture of the bridges came between 05:00 and 07:00, and consisted of isolated and often uncoordinated attacks by tanks, armoured cars, and infantry that grew in intensity throughout the day.

[24] Despite the ferocity of the attacks, the battalion and the coup-de-main force were able to hold the bridges until 19:00, when the leading elements of the British 3rd Infantry Division arrived and began to relieve the airborne troops, a process that was completed around 01:00 7 June.

When both units moved away from their rendezvous points neither had more than sixty per cent of their strength, although individual airborne troops and small groups would join the battalions throughout the day.

The 12th Parachute Battalion was bombarded with heavy mortar and artillery fire, and repelled two German counter-attacks by the 125th Panzer Grenadier Regiment; the first was defeated after destroying a tank and taking a number of prisoners, and the second was repulsed with the help of an air-landed anti-tank battery which had recently arrived.

[52] When the commanding officer, Alastair Pearson, arrived at the battalion rendezvous point at 01:20, he found only thirty paratroopers and a small group of sappers with a Jeep and trailer.

[53] Pearson therefore decided to send a small force to demolish the bridges at Bures, and lead the rest of the battalion to a crossroad north of Troarn where it would await more reinforcements before it attacked.

[55] A small group, led by the company commander, assaulted the fortifications outside Varaville that were manned by approximately ninety-six Germans supported by several machine-gun nests and an artillery piece.

The artillery piece inflicted a number of casualties on the small Canadian force, killing the company commander, and a stalemate ensued until 10:00 when the enemy garrison surrendered after being subjected to mortar bombardment.

[61][62] Otway launched the assault as soon as the first glider overshot the battery, ordering the explosives to be detonated to form two paths through the outer perimeter, through which the paratroopers attacked.

These tasks had been achieved despite the problems caused by a large number of the airborne troops being scattered throughout the operational area assigned, due to a combination of bad weather and poor navigation on the part of the pilots of the transport aircraft carrying them.

Glider-borne airborne troops also suffered from navigational errors, with ten of the eighty-five gliders assigned to the division landing more than 2 miles (3.2 km) from their landing-zones.

On 11 June, the 5th Black Watch launched an attack on the town of Bréville, but was met with extremely heavy resistance and was repulsed after suffering a number of casualties.