lives of the squadron's personnel than in the film. Historical accuracy The Royal Air Force (RAF) did not form a unit called "633 Squadron" during the Second World War. However, there was a 613 Squadron, equipped with Mosquitos, and credited with an attack on a Dutch Central Population Registry building on 11 April 1944, where the Germans held their Dutch Gestapo records. Furthermore, RAF Bomber Command undertook a variety of operations against German missile production facilities similar to that of the film - including Operations Crossbow, Bellicose, and Hydra. A multinational Allied war effort is depicted: in addition to an American central character, the film features members of the Norwegian resistance, airmen from India, New Zealand, and Australia. This reflects three historical facts: first, airmen of many nationalities joined the RAF proper; second, under the British Commonwealth Air Training Plan, airmen from Commonwealth air forces were frequently assigned to RAF units and; third, many squadrons belonging to Commonwealth air forces, or European governments-in-exile were under the operational control of the RAF during the war. The film draws from many of the real operations of 617 Squadron, in particular their attack on the German battleship Tirpitz in a Norwegian fjord, although that squadron used four-engined Avro Lancaster heavy bombers to carry the Barnes Wallis designed, 5.35-ton Tallboy earthquake bombs, not the twin-engined de Havilland Mosquitos depicted. However, the Mosquito was used by 618 Squadron in connection with another of Barnes Wallis' "bouncing bombs", called Highball. Though Highball was never used operationally, 618 Squadron was used as a special operations unit and is, probably, the closest match to "633". During the film, the pilots are briefed on using earthquake bombs, however the footage of the bombs arriving at the airfield clearly show the Mark I 1,800 kg (4,000 lb) Cookie. The delivery method, construction and effect of the two types of bomb are almost totally opposite. The Earthquake bomb must be released from high altitude for it to attain the necessary speed, and must have a heavy case to penetrate the ground. In the blockbuster bomb, the case is extremely light in comparison to allow maximum explosive payload to flatten buildings at or above ground level. The single-plane raid on Gestapo Headquarters to kill Erik before he talked bore similarities to the Oslo Mosquito raid. The original plot, however, is similar to a real RAF mission. The novel's plot did not mention