King of the Middle March - Kevin Crossley-Holland

It is 1202, and thousands of knights and footsoldiers are mustering in Venice for the Fourth Crusade. Among them is young Arthur de Caldicot, squire to Lord Stephen. It is thrilling to be part of this huge gathering; but as Christian falls upon Christian and Saracens draw their scimitars, Arthur's eyes are opened to the realities of war. Looking into his seeing stone for guidance, he realises that the exploits of King Arthur and his knights, like those of the crusaders, are as grim as they are glorious.
Meanwhile Arthur has his own concerns: Gatty, his betrothal, his dream of finding his mother, his relationship with his violent father and his churlish foster-brother. When he finally returns to England, all he has lost and all he has won come together.
War, romance, murder, family quarrels, power politics, the conflict between Christianity and Islam: all these are elements in a story packed with drama and colour. Its vivid picture of daily life in medieval times is shot through with earthy comedy and the magic of the Arthurian legends. Darker and deeper than the first two books, this is a marvellous ending to a trilogy that has utterly captivated its readers.