The Court now wished to temporise and overtures were made to De Retz to resign the archbishopric. He was offered in exchange the revenues of seven wealthy abbeys, but stubbornly refused. He was advised by his friends not to yield as the only means to recover his liberty, but he finally agreed to accept the proffered exchange and pending the approval of the Holy See was transferred from Vincennes to the prison of Nantes at the mouth of the Loire. Here his treatment was softened. He was permitted to amuse himself, to receive visitors of both sexes and to see theatrical performances within the castle. He was still a close prisoner and there was a guard of the gate sentinels on his rooms; but he bore it all bravely, being buoyed up with the hope of approaching release.
A bitter disappointment was in store for him. The Pope refused to accept his resignation on the grounds that it had been extorted by force and was dated from the interior of a prison. The attitude of his gaolers changed towards him as he was suspected of foul play and he was secretly apprised that he would probably be carried further out of the world and removed to Brest. He was strongly advised to attempt escape. One idea was that he should conceal himself in a capacious mule trunk and be carried out as part of a friend's baggage. The prospect of suffocation deterred the Cardinal and he turned his thoughts to another method. This was the summer season and the river was low and a space was left at the foot of the castle wall. The prisoner was in the habit of exercising in a garden close at hand, and it was arranged that four gentlemen devoted to him should take their posts here on a certain afternoon. There was a gate at the bottom of the garden placed there to prevent the soldiers from stealing the grapes. Above was a kind of terrace on which the sentries guarding De Retz were stationed. The Cardinal managed to pass into this garden unobserved and he came upon a rope so placed as to assist him in sliding down to the lower level. Here a horse was awaiting him, which he mounted and galloped away, closely followed by his friends. Their way led through streets where they encountered a couple of guards and exchanged shots with them. All went well until De Retz's horse shied at the glitter of a ray of sunlight, stumbled and fell. The Cardinal was thrown and broke his collar bone. Both horse and man were quickly got on their feet and the fugitive, though suffering horribly, remounted and continued his flight. The party reached the river in safety, but when embarking on the ferry-boat De Retz fainted and was taken across unconscious. There was no hope of his being able to ride further and while some of them went in search of a vehicle, the others concealed the Cardinal in a barn, where he remained for seven hours, suffering terribly. At last, help came, about two o'clock in the morning, and he was carried on a litter to another farm where he was laid upon the soft hay of a stack. He remained here until his safety was assured by the arrival of a couple of hundred gentlemen, adherents of the De Retz family, for he was now in the De Retz country. This successful escape caused much alarm in court circles, for it was feared that De Retz would reappear at once in Paris, but he was too much shaken by the accident to engage actively in public affairs. He remained in obscurity and at last withdrew from the country. He afterwards became reconciled to the royal power, serving Louis XIV loyally at Rome as ambassador to the Papal Conclave.