The prince kept his Christmas at Bordeaux.  Even during the winter his troops remained active.  Most of the Agenais was conquered by January, 1356, while in February the capture of Perigueux opened up the way of invasion northwards.  Meanwhile the prince mustered his forces for a vigorous summer campaign.  While the towns on the Isle and the Lot were yielding to his son, Edward III. was avenging the capture of Berwick by a winter campaign in the Lothians.  Before the end of January, 1356, Berwick was once more in his hands.  Thence he passed to Roxburgh, where Edward Balliol surrendered to him all his rights over the Scottish throne.  Thenceforth styling himself no longer overlord but King of Scotland, Edward mercilessly harried his new subjects.  But storms dispersed the English victualling ships, and Edward’s men could not live in winter on the country that they had made a wilderness.  In a few weeks they were back over the border, though their raid was long remembered in Scottish tradition as the Burnt Candlemas.

Another breach between Charles of Navarre and his father-in-law again opened to the English the way to Normandy.  John lost patience at Charles’s renewed intrigues, and in April arrested him and his friends at Rouen.  Thereupon his brother, Philip of Navarre, rose in revolt.  With him were many of the Norman lords, including Geoffrey of Harcourt, lord of Saint-Sauveur.  The English were once more invited to Normandy, and on June 18 Lancaster landed at La Hougue with the double mission of aiding the Norman rebels and establishing John of Montfort, then arrived at man’s estate, in his Breton duchy.  It was the first English invasion of northern France during the war, in which they had, as in Brittany, the co-operation of a strong party in the land.  The Navarre and Harcourt influence at once secured them the Cotentin.  Meanwhile, however, the French were besieging the fortresses of the county of Evreux.  With the object of relieving this pressure, Lancaster, immediately after his landing, marched into the heart of Normandy, and soon reached Verneuil.  It looked for the moment as if he were destined to emulate the exploits of Edward II. in 1346.  But he abruptly turned back, leaving the county of Evreux to fall into French hands.  The permanent result of his intervention was to reduce Normandy to a state of anarchy nearly as complete as that of Brittany.  In the autumn Lancaster at last made his way to the land of which he had had nominal charge since the previous year.  He left Philip of Navarre as commander in Normandy, and the war was supported from local resources.  The Cotentin being in friendly hands, Lancaster attacked the strongholds of the Blois party, which had hitherto been exempt from the war.  In October he laid siege to Rennes and was detained before its walls until July, 1357, when he agreed to desist from the attack in return for a huge ransom.  Lancaster then established young Montfort as duke.  At the same time Charles of Blois, released from his long imprisonment, once more reappeared in his wife’s inheritance, though, as his ransom was still but partly paid, his scrupulous honour compelled him to abstain from personal intervention in the war.  Thus Brittany got back both her dukes.