Operation Tonga was the codename given to the airborne operation undertaken by the British 6th Airborne Division between 5 June and 7 June 1944 as a part of Operation Overlord and the D-Day landings during the Second World War.
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. The division was to capture two strategically important bridges over the Caen Canal and Orne River which were to be used by Allied ground forces to advance once the seaborne landings had taken place, destroy several other bridges to deny their use to the Germans and secure several important villages. The division was also assigned the task of assaulting and destroying the Merville Gun Battery, an artillery battery that Allied intelligence believed housed a number of heavy artillery pieces, which could bombard the nearest invasion beach (codenamed Sword) and possibly inflict heavy casualties on the Allied troops landing on it. Having achieved these objectives, the division was then to create and secure a bridgehead focused around the captured bridges until they linked up with advancing Allied ground forces.
The division suffered from a combination of bad weather and poor pilot navigation, which caused many of the airborne troops to be dropped inaccurately throughout the divisional operational area causing a number of casualties and making conducting operations much more difficult. In particular, the 9th Parachute Battalion, which was assigned the task of destroying the Merville artillery battery, was only able to gather up a fraction of its strength before it had to attack the battery, with the result that the depleted force suffered heavy casualties. However, the battery was successfully assaulted and the guns inside it disabled. The division's other objectives were also achieved despite the problems encountered.
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. The other bridges were destroyed by the division, and a number of villages were occupied. 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.
Background
Operation Tonga originated in the planning of Operation Overlord, the Allied plan for the eventual invasion and liberation of German-occupied France. Invasion planning begun in May 1943, when President Franklin D. Roosevelt and British Prime Minister Winston Churchill met during the Washington Conference. The two Allied leaders decided that all available Allied forces should be concentrated in the United Kingdom, and that planning for the invasion of North-Western Europe should begin. A provisional target date of May 1944 was set with the code-name 'Overlord' decided upon. A joint Anglo-American planning staff was created under lieutenant-general Frederick E. Morgan, who was given the title of Chief of Staff to the Supreme Allied Commander (COSSAC).
Early drafts of Overlord called for the commitment of airborne forces to support the ground forces and protect their landing areas. Operation Skyscraper, for example, called for the deployment of two airborne divisions to support the beach landings that would be made by five infantry divisions. One airborne division would land near Caen, and another on the east coast of the Cotentin Peninsula. "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. Morgan and his staff finally decided that the invasion should take place along a thirty-mile front from the River Orne westwards. 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.
Following the appointment of General Sir Bernard Montgomery to the command of the 21st Army Group and overall command of all ground forces to land in Normandy, the plan underwent a number of further revisions. On 21 January 1944, a revised Overlord plan was presented to General Dwight D. Eisenhower, who had been chosen as the Supreme Allied Commander for the invasion. Montgomery's revised plan widened the landing area to include all of the coastline between the River Orne and the eastern coast of the Cotentin Peninsula; five divisions would land on the beaches, and supported by three airborne divisions to land on either side of the landing areas to secure their flanks and protect the landing troops from counterattack. The British airborne forces were assigned to the eastern flank, and the American airborne forces the west.
Prelude
British preparation The 6th Airborne Division, which was under the command of Major-General Richard Gale, was chosen to conduct the airborne operations on the eastern flank of the invasion area. The division was new, having been activated in April 1943, and Operation Overlord would be its first experience of combat. The division was the first to be established for the sole purpose of undertaking division-level airborne operations rather than contributing to a range of smaller operations, and there was considerable debate over what the unit should do.
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, reflecting the ongoing discussions at the strategic level over the wider plan for D-Day. On 17 February 1944, Major-General Frederick Arthur Montague Browning (commander of all British airborne forces) arrived at the 6th Airborne Division's headquarters to brief Gale on what the division was expected to achieve during the invasion; their role codenamed Operation Tonga.
The original plan for Tonga did not involve the entire division, instead only called for a single parachute brigade and an anti-tank battery to be attached to the British 3rd Infantry Division. This force would be tasked with seizing bridges over the Caen Canal and the River Orne near the towns of Bénouville and Ranville. Gale objected to this small-scale operation, arguing that a single brigade would not be able to achieve these objectives with such limited manpower, and asked for the entire division to be deployed. After consultation with his superiors, Browning agreed to the request and ordered Gale to begin planning for the operation.
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. First, it was to capture intact the two bridges over the Caen Canal and the Orne River at Bénouville and Ranville. The bridges then would be defended against counterattacks. Gale knew that the capture of the bridges would be critical for the resupply and reinforcement of his division, but he did not know that the bridges were incapable of supporting tanks. 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. The third mission was to destroy several bridges which spanned the River Dives, located near the towns of Varaville, Robehomme, Bures and Troarn. The division would then hold the territory that it had seized, until it could be relieved by advancing British ground forces.
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. Two Royal Air Force (RAF) air groups were provided for the operation to ensure that the division could be deployed in just two airlifts. The pilots and crew of these transport aircraft then began formation flying training and specialised aircrew training to ensure that they were as familiar with what the operation required of them. The 6th Airborne Division carried out several large-scale airborne exercises, using them to find the most efficient way to deploy a brigade group on one or multiple landing-zones.
On 6 February, the 3rd Parachute Brigade undertook an exercise in which the entire brigade was dropped by 98 transport aircraft. At the end of March, 284 aircraft were used in Exercise 'Bizz II' in which the entire division was deployed by parachute or glider. Between 21 April and 26 April, Exercise 'Mush' utilised approximately 700 aircraft to deploy the British 1st Airborne Division and the Polish 1st Parachute Brigade against the 6th Airborne Division, who moved by road, in a simulation of a full-scale airborne operation.
As the date of the operation approached, training became more intensive. 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. Once the pilots had practiced this sufficiently during the day, they were then switched to night operations. 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.
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. The force assigned to the coup-de-main operation, to capture the bridges over the Orne River and Caen canal, were transferred to Exeter. There, they conducted intensive exercises around the River Exe and the nearby canal that stood in place for their real objective.
The pilots of the gliders and transport aircraft were also constantly briefed with thousands of maps and photographs of the landing zones and the surrounding areas, as well as dozens of scale models of the zones and the primary objectives, such as the bridges and the Merville battery. 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.
German preparation
The 6th Airborne Division would be opposed by German Army (Heer) formations stationed in the area around Caen and the River Orne. By June 1944, this consisted of the 711th and 716th Infantry Divisions; both of which were static formations whose manpower consisted of medically downgraded troops and conscripts recruited from the Soviet Union or Eastern Europe. Both divisions also had a miscellaneous collection of anti-tank guns and artillery pieces, as well as a small number of German and French tanks and self-propelled guns.