From Chapter 6 of Prince Caspian:
…There came in sight the noblest creatures that Caspian had yet seen, the great Centaur Glenstorm and his three sons. His flanks were glossy chestnut and the beard that covered his broad chest was goldenred. He was a prophet and a star-gazer and knew what they had come about.
“Long live the King,” he cried. “I and my sons are ready for war. When is the battle to be joined?”
Up till now neither Caspian nor the others had really been thinking of a war. They had some vague idea, perhaps, of an occasional raid on some Human farmstead or of attacking a party of hunters, if it ventured too far into these southern wilds. But, in the main, they had thought only of living to themselves in woods and caves and building up an attempt at Old Narnia in hiding. As soon as Glenstorm had spoken everyone felt much more serious.
“Do you mean a real war to drive Miraz out of Narnia?” asked Caspian.
“What else?” said the Centaur. “Why else does your Majesty go clad in mail and girt with sword?”
I’m inclined to put this under priests because “the beard that covered his broad chest was goldenred” and under prophets because “he was … a star-gazer.” But the main point that Glenstorm makes, after all, is that his Majesty goes “clad in mail and girt with sword.” And so do we.