Why was the Duke’s first marriage invalid?

On November 6th, 1895, the Duke of Marlborough went through a marriage ceremony with an American girl, Consuelo Vanderbilt. Both were Protestants, and normally such a marriage would have been valid. However, Miss Vanderbilt had secretly promised to marry another man of her own choice, but the mother forced the girl to marry the Duke. The marriage was not a success, and they separated in 1905, by mutual consent. In 1920 they secured a civil divorce, and both married again. In 1925 the decision of the Catholic Church was sought as to whether the first marriage had ever been valid according to Christian principles. Rome sought all the evidence possible. Miss Vanderbilt’s mother deposed on oath, “I forced my daughter to marry the Duke, thinking her objections merely those of an inexperienced girl.” Her aunt deposed on oath, “This marriage was forced on the girl, who desired to marry someone else altogether.” Another friend of the mother deposed that “it was no question of persuasion, but of absolute constraint.” Rome could not but decide that, abstracting altogether from the civil decree of divorce, the parties had never really been married at all.

Radio Replies Volume 1 by Rev. Dr. Leslie Rumble MSC and Rev. Charles Mortimer Carty