“People of Camelot, for a great many years we have been mortal enemies, and the blood of our men stains the ground from the walls of Camelot to the gates of Mercia. And though we remember those who have died, we must not allow any more to join them.”
He warred with King Uther Pendragon for a long time before agreeing to a peace treaty, but his effort was temporarily stymied when he was framed by the sorceress Nimueh for the attempted assassination of Arthur Pendragon.
Bayard was therefore imprisoned for "poisoning" the prince. Bayard's forces were poised to attack Camelot for his imprisonment, but the truth was discovered by Gaius and Gwen in time to prevent war and Bayard was released. After Uther discovered Bayard was innocent, peace was reestablished between Camelot and Mercia (The Poisoned Chalice).
Agravaine told Arthur that his victory against Caerleon was not enough to deter the likes of Odin and Bayard and the countless others who covet Camelot's wealth, suggesting that he should force Caerleon to accept a treaty on his terms (His Father's Son).
Personality
Little is known of Bayard's personality but he seemed to be a man of his word since he hasn't done anything to subvert the peace treaty between Camelot and Mercia. Bayard seemed to be a king in which really respected his allies and really detest his enemies.
Abilities
Like his personality, little is known about his abilities. It is assumed, since he is king, that he is trained for combat by a sword. He kept it close as he was quick to wield it once he was accused of attempting to poison Arthur Pendragon.
Bayard was mentioned again in "His Father's Son" by Agravaine, who said he "covets Camelot's wealth", suggesting that, despite being allies, Bayard would still take the chance to attack Camelot, if he would find it weakened.
It is rumoured that Bayard will return in Series 5 but it is currently unclear as the actor who plays him only had one follower on Twitter at the time of his tweet.
