Bay City Belle by Shirley Kennedy

Before the war, Belle Ainsworth led a life of pleasure and privilege in the deep South. Five years after losing her fiancé at the Battle of Gettysburg, she is still alone, with no prospects for marriage among the remaining men of her acquaintance. But out west, there are possibilities. And when Belle answers an ad for a mail-order bride and boards a train to San Francisco to meet wealthy restaurateur Robert Romano, it’s with the hope of at last making her dreams of family come true.

When the train is robbed, Yancy McLeish, a disillusioned Union Army hero, rescues Belle from her attackers—and lays claim to her heart. But Belle has pledged her troth to Romano and intends to honor that commitment. It’s a decision she soon regrets, for her groom-to-be is nothing like his letters. As she plots a course to escape Romano, Belle prays that road can lead her back to the safety of Yancy’s arms, where she believes she was always destined to be…