 Complete the following phrase:  Laura married Louis at the Palais Royal in the French capital on 4 February 1651 and was thus became Duchess of Mercœur. Having married a legitimised prince of the blood, Laura was allowed the style of Serene Highness. However, she had a lower rank than that of her cousin the Princess of Conti who had married a legitimate prince. The young duke was instantly enamoured with his wife and his affections were returned. Three sons followed in quick succession the eldest of which being a famous commander in the wars of the Grand Alliance and 