Year 500 (D) was a leap year starting on Saturday (link will display the full calendar) of the Julian calendar. Events By Place Europe Possible date for the Battle of Mons Badonicus: Romano-British and Celts defeat an Anglo-Saxon army that may have been led by the bretwalda Aelle of Sussex or possibly Cerdic of Wessex (approximate date; suggested dates range from 490 to 510). Note: This battle may have influenced the legend of King Arthur. Possible date at which Fergus Mór begins his re… (More on 500)