Downton Abbey Era Marriages

Mary isn't the only woman getting marginalized by the entail (unbreakable property inheritance agreement) of her family's estate. The only way Mary's father, the Earl of Grantham, was able to save the estate from financial ruin when he originally inherited it was by marrying a rich American heiress (Mary's mother). But even though it was the Countess's money that saved the estate, the rules of the times made it so that her daughters would get nothing after her death, and the fortune would instead go to a man — even if that's a distant male cousin.