Bertrand du Guesclin
Bertrand du Guesclin (1320-1380), known as the Eagle of Brittany and the Black Dog of Brittany was a Breton knight and French military commander during the Hundred Years' War. He was Constable of France from 1370 to his death and in 1373 he invaded Jersey.
Attack on Jersey
In 1373 du Guesclin, accompanied by the Duke of Bourbon, led a large invasion force to Jersey. The Black Dog of Brittany – or, more accurately, La Dogue Noir de Brocéliande, the great Breton forest – overran the Island, capturing Grosnez Castle in the process. His forces also burned property and killed Islanders indiscriminately.
With no water supply and limited defences, Grosnez was no real obstacle. Le Château de Gorey, later known as Mont Orgueil Castle was well fortified. Du Guesclin's troops tunneled under the outer walls but the inner walls were built on rock and they could make no further progress. Warden of the Isles Sir William Asthorpe and Bailiff Richard de St Martin knew that they could not withstand a long seige and negotiated with du Guesclin, saying that the castle would surrender in two months if reinforcements did not arrive. Hostages were given, as was common in such agreements in medieval warfare.
Sir William’s wife, Margaret Dynham, came originally from the Dinan area where du Guesclin was born and may have interceded on behalf of the Island.
Fortunately an English fleet arrived in time to lift the siege, but for two more years the island was constantly attacked by the French until an arrangement was arrived at that they would pay a ransom for du Guesclin to cease hostilities.