The High King by Lloyd Alexander, 285 pages

In this magnificent finale to the chronicles of Prydain, the whole land is the stage for the ultimate clash between the forces of good and evil which determines the fate of Prydain and of Taran, the Assistant Pig-Keeper who wanted to be a hero.
The last and greatest quest of Taran and his companions begins when the sword Drnywn, the most powerful weapon in the kingdom, falls into the hands of Arawn Death-Lord, threatening Prydain with annihilation. Taran and Prince Gwydion raise an army to march against Arawn's terrible cohorts, human and inhuman, in a decisive struggle which may be their last. After a winter march filled with danger, the challenge of battle and the tragedy of defeat, love and sorrow. Taran and his army finally arrive at the very portal of Annuvin, Arawn's stronghold and, ultimately, to a decision for Taran that is the most crucial of his life.