All Other Nights by Dara Horn

This is the story of Jacob Rappaport, a Jewish soldier in the Union army during the Civil War. Jacob joins the army to escape family expectations, but has to examine his beliefs and loyalties when he is recruited by the army to be an assassin and a spy. Although the book is fiction, it is based on real people and events. It's a very human story about love and family and betrayal, as well as the larger social issues that framed the Civil War. I recommend it.