The biography of Alexander by Oxford University professor Robin Lane Fox was an original inspiration and source of information for director Oliver Stone. As an historical advisor, Professor Fox didn't get an on screen credit; his price for giving his advice was to be allowed to take a place at the head of what is one of the largest cavalry charges ever filmed. Professor Fox was used to riding around the English countryside, but gladly dressed up as a Macedonean cavalry officer to live his dream of charging for Alexander.