Book Suggestions - The Dove in the Eagle's Nest

Book Suggestions - "The Dove in the Eagle's Nest"
Charlotte Mary Yonge
There was a time when feudal lords still believed that a castle could be impenetrable. When nature alone was thought to be defense enough. There was a time when there was only one Christian Church in all of Europe. There was a time when even a Lord of Europe might be stolen away to become a slave a world away. But the fifteenth century has begun. The sounds of cannons boom over mountain fortresses. Scattered city-states are becoming empires.  In the depths of Germany questions are stirring.
Two women, baronesses, stand in a mountain crag. One holds that her Eagle's Nest is invulnerable. The other has seen the power of the dawning scientific age. One stands for the world that was. One for the world that will be. 
Take a step back in time to a world in the middle of multiple revolutions.