HOW DID HE DIED?
When Arthur returned back, he found Mordred on his throne so he faced with him to get the throne in the famous battle of Camlann. Mordred and Arthur faced to dead, Arthur killed his son but he left Arthur mortally injured. Time after Arthur died.
Is said that Morgana ordered Arthur’s body to be moved by a boat through the river Avalon and Merlin picked it on the other side of the river. others say that his boat was send from Cornualles to Ireland where they say that may be buried.