From 1590–98, during the War of the Catholic League, Philippe Emmanuel, Duke of Mercœur (governor of Brittany and husband of the countess of Penthièvre) sought to have himself proclaimed Duke of Brittany and allied with Philip II of Spain.
Entre 1590 e 1598, durante a guerra da Liga Católica, Philippe-Emmanuel, Duque de Mercoeur (gobernador da Bretaña e marido da condesa de Penthièvre) tentou ser proclamado Duque da Bretaña e aliouse con Filipe II de España.