User blog comment:Morgana High Priestess/Which reign is better: Uther's or Arthur's?/@comment-5933518-20130120235922/@comment-5674726-20130121002139

They both brought peace with the other kingdoms (Uther with the kingdom of Mercia, Arthur with the kingdom of Caerleon and Nemeth).

Don't forget that Uther also achieved a peaceful accord with Cenred, one that was only broken at Morgause's instigation, as well as peace between the Five Kingdoms. There was also peace with Caerleon in Uther's day, and war was threatened after Arthur executed their King.

Peace with Nemeth was bought at the cost of all disputed territory being surrendered to Nemeth, not to mention the loss of the possibility of the two kingdoms being united. Arthur is very lucky that Mithian and her father didn't take offence when he rejected her after bringing her to his kingdom as his betrothed, and making it publicly known that he intended to marry her.

I would imagine that other monarchs in King Rodor's position would consider it very insulting if their daughter's engagement progressed to the point where she was brought to her future husband's kingdom, only for her to be rejected in favour of a servant girl. It was potentially a diplomatic disaster.