With the resumption of war between France and England in 1369 Charles saw fresh opportunities to increase his status in France. He left Navarre and met John V, Duke of Brittany in Nantes, where they agreed to come to each other's aid if either was attacked by France. Basing himself in Cherbourg, the principal town in what remained of his territories in Northern Normandy, he then sent ambassadors to Charles V of France and Edward III of England. He offered to aid the French King if he would restore his former territories in Normandy, recognize his claim to Burgundy and bestow the promised lordship of Montpellier. To the English King he offered an alliance against France whereby Edward III could use his territories in Normandy as a base to attack the French. As on previous occasions, Charles did not really want an English army on his lands; he wanted the threat of one to put pressure on Charles V. But Charles V refused his demands outright. On the strength of Charles of Navarre's offers Edward III despatched an expeditionary force to the Seine estuary under Sir Robert Knolles in July 1370. He invited Charles to come to England in person – which he did during that same month. Charles of Navarre entered into secret negotiations with Edward III at Clarendon Palace, but committed himself to very little. Simultaneously he continued to negotiate with Charles V, who feared the King of Navarre would throw in his lot with Knolles's army now operating in Northern France. Though Edward III sealed a draft treaty with Navarre on 2 December 1370 it was a dead letter after the destruction of Knolles's army at the Battle of Pontvallain a few days later. In March 1371, seeing no option left, Charles of Navarre had a series of meetings with Charles V and did homage to him.