French School, (16th century); French. Medium: engraving. Bertrand du Guesclin (c.1320-80) known as 'Eagle of Brittany' or the 'Black Dog of Broc�liande', was a Breton knight and French military commander during the Hundred Years' War. He was a Constable of France from 1370 until his death. Bertrand du Guesclin Comte de Longueville Conestable de France. Provenance: Private Collection. Photographic Rights The Bridgeman Art Library.