Mazo de la Roche 
Morning at Jalna [PDF ebook] 

First published in 1960, in Morning at Jalna it is 1863 and the American Civil War is raging south of the border. Still in its early years, the Jalna estate seems far away from the despair and destruction. Philip, who will grow up to become the master of Jalna, has just come into the world, while Augusta, Nicholas, and Ernest are children. Life at Jalna is as peaceful as usual until the Sinclairs come to visit. They arrive with the polished manners and soft accents of Old Carolina and quickly appeal to Adeline’s sense of hospitality. However, as the burden these distant cousins bring grows, the Whiteoaks begin to suspect that the Sinclairs have a deep and dangerous secret. This is book 2 of 16 in The Whiteoak Chronicles. It is followed by Mary Wakefield.