 On 19 January 1559, at the age of 11, she married Charles III, Duke of Lorraine in the cathedral of Notre Dame in Paris.The marriage was arranged as a symbolic union of peace between France and Lorraine, after Charles III had spent his childhood as a hostage at the French royal court, and completed after the Treaty of Chateau-Cambresis.Claude departed to Lorraine with her spouse in late 1559, shortly before the departure of her sister Elisabeth to Spain and her aunt Marguerite to Savoy.