If you enjoy historical fiction "Here Be Dragons" is a must read.  Sharon Kay Penman is a master of historical fiction and you will find that her work is as close to historical accuracy that you will find in any work of fiction.  I also enjoyed her treatment of John Lackland as more than a sinister character.  Below is the summary you will find on Amazon .

Thirteenth-century Wales is a divided country, ever at the mercy of England’s ruthless, power-hungry King John. Llewelyn, Prince of North Wales, secures an uneasy truce by marrying the English king’s beloved illegitimate daughter, Joanna, who slowly grows to love her charismatic and courageous husband. But as John’s attentions turn again and again to subduing Wales---and Llewelyn---Joanna must decide where her love and loyalties truly lie.

The turbulent clashes of two disparate worlds and the destinies of the individuals caught between them spring to life in this magnificent novel of power and passion, loyalty and lies. The book that began the trilogy that includes Falls the Shadow and The Reckoning, Here Be Dragons brings thirteenth-century England, France, and Wales to tangled, tempestuous life.