Having returned to France, "Mademoiselle de Nemours" caught the attention of the dashing Prince Charles of Lorraine, heir of the Duke of Lorraine. The court of Portugal had previously requested her hand in marriage, however she refused after some deliberation on the subject. Charles' rank was similar to that of the Duke of Savoy and the match was pursued by Marie Jeanne Baptiste's mother. She became engaged to Charles on 4 February 1662. The match was a popular one with the French court, and the union was supported by Queen Anne (mother of Louis XIV). However, when the Treaty of Montmartre was signed two days later, the duchies of Lorraine and Bar were surrendered to Louis XIV. This left the duke of Lorraine landless, and drove him to join the imperial court. As a result, Charles backed out of the engagement. The marriage between Marie Jeanne Baptiste and Charles had not been consummated and was annulled.