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