The Forgotten Secret by Kathleen McGurl

Clare is a woman in modern England stuck in a miserable marriage with her controlling husband of 25 years. When she inherits a farm in Ireland, she jumps at the chance for a separation to find happiness and independence of her own. In pursuing her favorite hobby of restoring old furniture, she finds a birth certificate and an old medallion stuffed in an old chair. She decides to research the history of these objects with the help of the local bookseller.
Ellen, a young Irishwoman in the early 1900s, starts a new job as a servant to a woman who was an active nationalist Irish volunteer. She has fallen in love with her longtime friend and neighbour Jimmy, who is also a volunteer, and is disappointed that he refuses to marry her until Ireland is free. She feels compelled by both of them to assist with the war effort.
I like that Clare finally freed herself from her abusive marriage. Paul is such a controlling, horrible character in this book. It's so sad that Ellen lost everything and never found out the truth in the end. Great historical fiction about Irish history I haven't read much about before.