He was one of Arthur's knights and also a lover to his evil sister Morgan le Fay, but she was married to King Uriens of Gore, and wanted to have her husband and brother killed and put Accolon on the throne as King of Britain. To start with she took Arthur's sword Excalibur.

When Arthur, Uriens and Accolon one day were out hunting she threw dust in their eyes and they couldn't find their way home but came to a beach, a boat was waiting and the crew were only beautiful women. The three gentlemen went on board and were well recieved, but when they woke up the next morning they weren't in the boat anymore.

Uriens woke up in his home with his wife's arms around him, Arthur in a dungeon at Damas the knight's place, who took knights in capture with the hope that one of them would help him win over his brother Ontzlake, who's father's heritage he had taken. After being convinced by his prison-friends he said he would stand up for Damas.

Accolon, finally, woke up by a road where a dwarf gave him Excalibur with blessings from Morgan le Fay, and there he met Ontzlake, who had got the challenge from Damas but he wasn't in the shape of accepting the challenge himself. Accolon said he could do it for him, and that is how Arthur and Accolon, with the visirs down, met in a single combat without the other one knowing who their combatant were. Accolon wounded Arthur with his own sword Excalibur och would've killed him if a fairy who were skilled in magic had not inteferred and made him drop the sword which Arthur took right away.

Another source gives the information it was the Nimue, Lady of the Lake - not a fairy - who caused Excalibur to fall to the ground using her magic skills.

Upon recognizing Arthur, the dying Accolon confessed all and begged forgiveness. Arthur forgave him, put the body on a 'horse-stretcher' and sent his dead body to Morgan's castle as "a present" before Arthur himself went to a convent for nuns to take care of his wounds. Morgan le Fay went there in an attempt to take Excalibur again and succeeded to get a hold of the scabbard, which protected its wearer from bleeding to death. Arthur followed her, and when she noticed that she was followed she threw the scabbard in the lake.

The source telling about Nimue also gives the information that Arthur had Accolon buried at St. Stephen's Church in Camelot.