The Dukes and Duchesses of Brittany between 1485 to 1559 were also kings and queens of France from the time France conquered Brittany to the death of King François II of France.
Anne of Brittany, the last truly independent Duchess of Brittany, fought her whole life to keep her duchy separate from France. She had only limited success. When she died, her elder daughter, Claude married the heir to the French throne, Duke François d’Angoulême. When Anne died Claude became Duchess of Brittany. She kept it independent despite King François’s attempts to wrest it from her. Brittany passed to her elder son, François during her lifetime. However, he died before he became king.
Duchess Anne of Brittany, Duchess Claude of Brittany, and Duke François III of Brittany were crowned in separate coronations in Nantes. Brittany was not yet an appanage of the French crown. However, once Duchess Claude died, Brittany lost its independent status.
A list of the rulers during the period, with the dates of their reign and their spouses: François II, Anne, Claude, François III and Henry
Source: Tudor Times | Dukes & Duchesses of Brittany (1485 – 1559)