The Winter King (The Arthur Books #1)

Uther, the High King of Britain, has died, leaving the infant Mordred as his only heir. His uncle, the loyal and gifted warlord Arthur, now rules as caretaker for a country which has fallen into chaos - threats emerge from within the British kingdoms while vicious Saxon armies stand ready to invade. As he struggles to unite Britain and hold back the Saxon enemy, Arthur is embroiled in a doomed romance with beautiful Guinevere.