Procedures pioneered by William Thornton Mustard (born 8 August 1914 in Clinton, Ontario) had a historic impact on the field of surgery. He attended the University of Toronto Schools and the University of Toronto Medical School. During WWII while Mustard was stationed in England, the value of his work in the repair of damaged leg arteries was recognized by his appointment as a member of the Order of the British Empire. He joined the staff of the Hospital of Sick Children in 1947 where he specialized in paediatric surgery. In 1951, his innovative muscle transfer procedure for children disabled by polio minimized their need for crutches bringing international recognition. He moved exclusively into the field of paediatric cardiac surgery in 1957 and five years later performed the first surgery to correct transposition of the great vessels of the heart, a previously fatal congenital defect. In April 1976 he was invested as a member of the Order of Canada. He died 11 December 1987.