633 Squadron is a 1964 war film directed by Walter Grauman and starring Cliff Robertson, George Chakiris, and Maria Perschy.

The plot, which involves the exploits of a fictional World War II British fighter-bomber squadron, was based on the 1956 novel of the same name by former Royal Air Force officer Frederick E. Smith, which itself drew on several real RAF operations.

The plant is in a seemingly impregnable location beneath an overhanging cliff at the end of a long, narrow fjord lined with numerous anti-aircraft guns.

The only way to destroy the plant is by bombing the cliff until it collapses and buries the facility, a job for 633 Squadron's fast and manoeuvrable de Havilland Mosquitos.

Back in Britain, Davis tells a fellow officer who is aghast at the losses, "You can't kill a squadron".

Originally a project for director John Sturges, he initially worked on a script with Rod Serling of The Twilight Zone fame as early as 1958 and offered Jack Lord the leading role.

When Robertson expressed reservations about the story, producer Walter Mirisch engaged U.S. scriptwriter Howard Koch, resident in London, to rewrite the film to placate him.

[10] The riverbank where Robertson's character romances Maria Perschy was Hurley Lock on the River Thames and was also used in a similar early scene in From Russia with Love.

[3] Grauman's wartime experience as a North American B-25 Mitchell bomber pilot helped create an authentic aviation epic.

As the Royal Air Force had retired the type in 1963, civilian operators mostly leased former converted bomber examples (TT Mk 35) to the RAF for target-towing.

[14] Scouring RAF airfields at Exeter, South Devon, Henlow, Shawbury and the Central Flying School at Little Rissington provided not only ten authentic aircraft but also vehicles and equipment from the war.

The TT 35 models had their clear nosecones and side windows painted over and dummy machine gun barrels fitted.

[19] Although the film made extensive use of real flying aircraft, special effects were needed to create the final attack scenes.

Oscar winning special effects technician Tom Howard used miniatures, front and rear projection and matte paintings to make the sequences work.

[20] Cliff Robertson enjoyed working on the film and stated that the atmosphere on set was very good, but was unhappy with the ambiguous ending.

Robertson was cast because he was popular internationally at the time and because an American central character improved the production's access to finance and worldwide audiences.

Additionally, Robertson was an experienced pilot, owned a Supermarine Spitfire, and was personally interested in making the film as an accurate portrayal of wartime flying.

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.

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 novel's plot did not mention the nature of the target, only that it was a highly rated objective in Norway that could not be reached by the RAF until the Mosquito became operational.

Typical of the mineral wealth that Hitler stated was worth the sacrifice of a significant portion of the Kriegsmarine, Knaben could produce four-fifths of Germany's requirements for molybdenum, an important element in the production of armour plate.

The mine at Knaben was too small to hit in a night raid, and sending heavy, long-range bombers in daylight would have met with disaster.

[29] The "jeep" partly hidden behind a bush in one of the Scottish Highlands training sequences is a post-war Land Rover, and the "German halftrack" is an Alvis Saracen.

While critics derided the wooden acting and hackneyed plot, and the use of the miscast Mirisch Pictures contract star George Chakiris, the aerial scenes were considered spectacular and with Ron Goodwin's music remained the main attraction.

[37] The musical score of 633 Squadron was written by the British composer Ron Goodwin and became very popular and well known to the public after the film's initial release.