 Complete the following phrase:  The Horsa was used in large numbers by the British Army Air Corps and the Royal Air Force RAF; both services used it to conduct various air assault operations through the conflict. The type was used to perform an unsuccessful attack on the German Heavy Water Plant at Rjukan in Norway, known as Operation Freshman, and during the invasion of Sicily, known as Operation Husky. Large numbers of Horsa were subsequently used during the opening stages of the Battle of Normandy, being used in the British Operation Tonga and 