The Dragon and the Fair Maid of Kent - Gordon R. Dickson

Jim Eckert, the Dragon Knight, must now confront the three disasters that lie in wait for any visitor to the English Middle war, plague, and Plantagenets. The plagues is caused by a covert invasion of shape-shanging goblins with plague-tipped spears that seek to take over the world. Meanwhile, Eckert's castle is invaded by Edward III, his son Edward the Black Prince, and Joan, the Fair Maid of Kent. Against the background of a full-scale human-versus-goblin war, these worthies move in a swirl of intrigue and dynastic tension. And, as usual, it's up to the Jim Eckert, in all his scaly glory, to make sure good triumphs in the end!