During the late 1950s and 1960s there was a significant rationalisation of all aspects of British aerospace and this included aero-engine manufacturers. In 1966 Rolls-Royce acquired Bristol Siddeley (which had resulted from the merger of Armstrong Siddeley and Bristol Aero Engines in 1959) and incorporated it as the Bristol Siddeley division. Bristol Siddeley, with its principal factory at Filton, near Bristol, had a strong base in military engines, including the Olympus, Viper, Pegasus (vectored thrust) and Orpheus. They were also manufacturing the Olympus 593 Mk610 to be used in Concorde in collaboration with SNECMA. They also had a turbofan project with SNECMA.