The Coronation of Queen Morgana

The Coronation of Queen Morgana was the 'ceremony' that saw Uther Pendragon's secret daughter, Morgana become queen after she and her half-sister Morgause over took over Camelot for the first time.

Background
During the events of The Crystal Cave, Merlin sees Morgana attempt to kill Uther so he attempts to stop which results in her falling down a flight of stairs and almost killing herself. Uther, desperate to save her tells Gaius of her true heritage and that he (Uther) is in fact Morgana's father not Gorlois like originally believed leaving Morgana, who was on death's doorstep to overhear this. Once she recovered (thanks to Merlin's healing spell), she reported this to her half-sister Morgause, who was overjoyed by the news telling a confused Morgana that she had a claim to Uther's throne like Arthur did as she was older than Arthur. After this, Morgana strongly believed that the crown was rightfully hers.

With the help of King Cenred, Morgause and Morgana manage to overthrow Uther and reveal Morgana's betrayal which devastates him gratefully though the sisters are unaware that Arthur and Merlin are watching overhead. Merlin and Arthur are forced to flee with their friends namely Gwaine, Elyan and Gaius while Gwen is forced to remain in Camelot and serve her now former best friend. During this time, Arthur sulks and wonders why Morgana would betray them.