Bertrand du Guesclin (c. 1320 – 13 July 1380), nicknamed "The Eagle of Brittany" or "The Black Dog of Brocéliande", was a Breton knight and French military commander during the Hundred Years' War. He was Constable of France from 1370 to his death. Well known for his Fabian strategy, he took part in six pitched battles and won the four in which he held command.