Only in Her Dreams by Veronica Towers
Blurb: Marcus Derning, Duke of Allendale and former Captain in the 73rd Foot Brigade, owes his life to the timely intervention of Sergeant Montague – an intervention which cost the man his life. What better way to honor the man’s memory but by marrying his daughter… if she would only have him? Sarah knows that duty and honor are poor substitutes for love and that a captain cannot marry the daughter of a common soldier, much less a common soldier’s daughter marry a Duke. Even deep in her heart where her irrational hopes linger, she knows the only way she could ever be with Marcus is Only in Her Dreams.