The coronation is a splendid ceremony. It feels more like a birthday to Wart because of all the presents he receives. There had been some revolts at first, from the Barons and the Gaels, but most soon settled down. The best present Wart receives, however, is a dunce's cap from Sir Ector. When Wart lights it at the top end, as you are supposed to, Merlyn appears standing before him.
White glosses over the coronation and how certain revolts are quelled. His writing mimics the way in which Wart experiences this period of time—strange, confusing, and incoherent.
Merlyn tells Wart that his father had been King Uther Pendragon. Merlyn, disguised as a beggar, had delivered Wart as a baby to Sir Ector's Castle—but he had been unable to tell Wart until now. Merlyn tells Wart how he already knows the joys and sorrows before him, how no-one will ever address him as Wart again and that from here on he will be known only as King Arthur.
It now comes out that Wart is the rightful heir to the throne and that he was disguised as a lowly squire his whole life. Once more, Merlyn had known and seen all this and knows much more of what will happen to Wart as King Arthur. We are left knowing that Arthur is fated and that his life is already set.