In July, 1373, John of Gaunt marched out of Calais with one of the strongest armies with which an English invader had ever entered France.  Pursuing a general south-easterly direction, the English pitilessly devastated Artois, Picardy, and Champagne.  Du Guesclin hastened back from Brittany to command the army engaged in watching Lancaster.  He still continued his defensive tactics, but gave the enemy little rest.  Lancaster was no match for so able a general as the Breton constable.  At the end of September he moved from Troyes to Sens, and thence pushed into Burgundy.  Then he turned westwards through the Nivernais and the Bourbonnais, and led his army through the uplands of Auvergne.  By the end of the year he had traversed the Limousin, and made his way to Bordeaux.  Half his army had perished of hunger, cold, and in petty warfare.  The horses had suffered worse than the men, and the baggage train was almost destroyed.  Without fighting a battle Du Guesclin had put the enemy out of action.  Experience now showed how useless were the prolonged plundering raids which ten years before had filled all France with terror.

Even in Gascony Lancaster could not hold his own.  After declining battle with the Duke of Anjou, he returned to England, leaving Sir Thomas Felton as seneschal.  The enemy had penetrated to the very heart of the old English district.  La Reole opened its gates to them; Saint-Sever, the seat of the Gascon high court, followed its example, By 1374 the English duchy was reduced to the coast lands around Bayonne and Bordeaux.  That year the French laid siege to Chandos’s castle of Saint-Sauveur-le-Vicomte.  The siege was as long and as elaborately organised as the great siege of Calais.  A ring of bastilles was erected round the doomed town, and cannon discharged huge balls of stone against its ramparts.  After nearly a year’s siege the garrison agreed to surrender on condition of a heavy payment.  With the fall of the old home of the Harcourts the English power in Normandy perished.  There was still, it is true, the influence of Charles of Navarre; but that desperate intriguer had compromised himself so much with both parties that no confidence could be placed in him.

The misfortunes of the English inclined them to listen to proposals of peace.  Though the papacy was more frankly on the French side than ever, it had not lost its ancient solicitude to put an end to the war.  With that object Gregory XI, though eager to return to Rome, tarried in the Rhone valley.  Two of his legates appeared in Champagne at the time of John of Gaunt’s abortive expedition.  From that moment offers of peace were constantly pressed on both sides.  Lancaster was at Calais, and Anjou was not far off at Saint-Omer, when definite proposals were exchanged.  Before long it was found more convenient that the envoys should meet face to face, and for this reason the two dukes accepted the hospitality of Louis de Male, and held personal interviews at