Avignon
Later that year, following the death of Cardinal Bernard d'Albi of Pamiers on 13 (or 23) November 1350, Cardinal Guy was translated to the suburbicarian diocese of Porto and Santa Rufina. Baluze remarks that Cardinal Guy was only the second senior Cardinal-priest, but that his senior, Cardinal Guillaume d'Aure, had never been a bishop, whereas Cardinal Guy had been consecrated ten years earlier. Preference at that time was given to cardinals who had been bishops, and therefore Cardinal Guy was promoted.
In 1351, from his prison in Prague, where he had gone to seek support from the Emperor Charles IV, Cola di Rienzi wrote a letter to Guy requesting his assistance in obtaining his freedom and leading a crusade. He was instead brought as a prisoner to Avignon, where he was put on trial for heresy. Somewhat surprisingly he was acquitted.
On 15 May 1352, Cardinal Guy was present at the Curia in Avignon, where he presided over the blessing of the new Abbot of l'Isle-Barbe near Lyon, Jean Pilfort de Rabastencs. On 12 November 1352, he was appointed Dean of S. Martin in Tours, which he held for life.
Pope Clement died in Avignon on 6 December 1352. The Conclave to elect his successor opened on Sunday, 16 December 1352 in the Apostolic Palace in Avignon, with twenty-six cardinals in attendance, including Guy de Boulogne. At mid-morning on 18 December they elected Cardinal Étienne Aubert, who took the name Innocent VI. He was crowned on 30 December 1352.
Immediately after his coronation on 30 December 1352, the new Pope, Innocent VI, appointed Cardinal Guy as the principal facilitator in negotiations between the English and the French for an end to the war. Frequent meetings took place at Calais and Boulogne. Cardinal Guy was attempting to use all of his credit with the French monarchy to bring about a peace with England, which would greatly enhance his prestige. He seems to have gone somewhat too far and he nearly succeeded in alienating the French King, who was disappointed at the proposed concessions. At the same time Cardinal Guy did succeed in arranging a peace between the French King and Navarre. But then King Edward III of England also made a treaty with the French claimant to the Duchy of Brittany, to the great discomfort of King John. During the negotiations, when he was in Paris, on 16 September 1353, the Cardinal dedicated the Carmelite Church in Paris, with the King, John II, and Queen Jeanne attending. On 6 April 1354 at Guînes, Cardinal Guy de Boulogne witnessed the signing by representatives of France and England of a preliminary accord for ending the Hundred Years' War. The preliminary accord had no lasting effect. The Battle of Poitiers took place on 19 September 1356, and King John II was captured by the Black Prince. The government of France collapsed.
