On a cripplingly hot day at the start of July 1187, Saladin, the sultan of Egypt and Syria, stood beside his son al-Afdal and peered across the battlefield towards a red tent on a hill. The sultan's face was pale with worry. The armies before him had been fighting for hours, tortured by near-unbearable heat, dust and smoke, which billowed up from the desert scrub Saladin's own men had set alight. Thousands of men and horses lay dead. The enemy – a vast force led by the Christian king Guy of Jerusalem – was badly battered and falling back, but until the king's red pavilion fell, victory would not be complete.