The duel between Arthur and Derian occurred after Arthur invoked the right of single combat to settle the war between Camelot and Caerleon.
Events
After Annis agreed to settle their dispute by single combat instead of war, Arthur appointed himself Camelot's champion while Annis chose Derian to act as Caerleon's. Initially, Arthur and Derian proved evenly matched, but unbeknownst to Arthur, Morgana had allied herself with Caerleon and had placed an enchantment on his sword that would make it too heavy for him to wield.
Once Morgana activated the enchantment, Arthur was left vulnerable to Derian's attacks. At this point, Merlin began using his magic to protect Arthur by causing Derian to freeze mid-strike and later to drop his sword.
Arthur grabbed the weapon and sliced Derian across the back, then kicked him to the ground and prepared to finish him off. Because he sought peace rather than victory, however, he chose to spare Derian and merely ran the sword into the ground by his head (His Father's Son).
Trivia
- This duel shares many similarities with the Old Testament story of David and Goliath.
- Arthur's decision to spare Derian later led to a longterm alliance between Camelot and Caerlon (Arthur's Bane).