So there has been no law here...can we have a true king please?
It's looser than I thought.
King Uther has his first born son, but a deal he made with Merlin takes his son away. King Uther later dies due to a traitors poison.
Sorry brother, here it is!
Arthur where have you been? Where is my sword?
A deal is made between Merlin and the archbishop to bring King Uther's son back to Britain, and he creates a sword only the true king can pull out. A messenger is later sent to all small places near London inviting them to London, including Arthurs home.
After Arthur and his family make it to London, they compete in the tournament, and their team wins. However in the next round Arthur loses his brothers sword, and has to find one, leading him to pull the sword from the stone.
Arthur presents the sword to his brother, and his brother claims to his father that he pulled the sword from the stone, but his father tells him to put it back in to see if he is the king. He fails though and tells Arthur to do it, Arthur does it and his father realizes who he is.
The archbishop makes him the king of Britain, but the other kings don't like this, and demand a turn at pulling the stone. They all fail after six more tournaments of Arthur proving himself.
Arthur is declared king of Britain, and rules the land. He goes on to live through many other adventures.