Grace Livingston Hill 
The Big Blue Soldier [PDF ebook] 

Aunt Marilla Chadwick wants to find a young man for her lovely young friend, Mary Amber. She sees a tall young soldier walking slowly toward her house. It doesn't matter that his uniform is bedraggled and dirty or that she had never seem him before in her life, for Aunt Marilla has an idea, a plan, a sudden inspiration–and soon she, Mary Amber, and the mysterious soldier are all entangled in an adventure that will change their lives forever.
It’s a story about hope, rejection, rescue, and several different kinds of love.