His mother, Françoise de Luxembourg (died in 1557), came from a younger branch of the House of Luxembourg, the Ligny-Brienne-St-Pol-Fiennes. She is the daughter of James II of Luxembourg, Count of Gavre, and Marguerite of Bruges, herself daughter of John V of Bruges, Lord of Gruuthuse. Charles V made her Princess of Gavre in 1535, after she inherited the domain of Gavre, located in East Flanders, from her brother Jacques III of Luxembourg, who died in 1532 without issue. Wanting to break the supremacy of Charles V, the King of France Henry II broke the truce of Vaucelles and invaded Artois. At the head of 60,000 men, Emmanuel-Philibert of Savoy, lieutenant general of the Netherlands, marched on the fortress of Mariembourg, occupied by the French. By pure tactics, he let the reinforcements.