Sister Queens, an insightful and engrossing dual biography, contrasts the lives of Catherine of Aragon, the first wife of Henry VIII, and Juana, Queen of Castile, both daughters of Spanish rulers Isabel I and Ferdinand II who are best known for their patronage of Christopher Columbus and their establishment of the Spanish Inquisition. The boundaries of Europe were still very fluid and Catholicism was splitting apart when Catherine and Juana dutifully left their childhood home to strengthen Spain’s position in the world by marrying Henry VIII’s short-lived older brother Arthur and Phillip of Burgundy. If you thought Catherine was weak, dull, shrewish and/or frumpy this book will change your mind about Henry VIII’s first wife, who comes across as intelligent, resourceful, strong and cunningly diplomatic. In the early days of Henry VIII’s reign she ruled England in his stead and led his armies against Scotland while Henry was dallying in a souped-up war with France. Juana who became a Queen in her own right nevertheless spent most of her adult life under the supervision of her husband, father and then son, Charles V, who was selected to be the ruler of the Holy Roman Empire, because it served their own interests better if they pretended she was mentally ill. Though Juana is the less known of the two sisters and never wielded much power herself, her children and grandchildren sat on thrones in countries as far away from Spain as Denmark, Austria and Hungry while Catherine’s line ended with her daughter Mary's death after a short reign as England’s Queen. Catherine and Juana come to life in this fascinating book set during a transitional time in Europe’s history.