Judith Pella 
Dawning of Deliverance (The Russians Book #5) [EPUB ebook] 

Though she is the daughter of a princess, Mariana was raised as a peasant and decides not to take up aristocratic life. Trained as a nurse, she goes to the front lines instead where she’s confronted with the realities of war–and encounters a man who once betrayed her. Can Mariana learn to trust him now? And will she and her family survive a dangerous new threat?