He was forced to leave Paris, in 1413, for some misconduct.  It was then that Cauchon became a strong partisan of the Duke of Burgundy.  It was through the Duke that he obtained the See of Beauvais.  The English also favoured Cauchon, and obtained for him a high post in the University of Paris.  When the tide of French success reached Beauvais, in 1429, Cauchon was obliged to escape, and found shelter in England.  There Winchester received him with cordiality.  While in England, Cauchon became a thorough partisan of the English, and the humble servant of the proud Prince-Cardinal.  Winchester promised Cauchon preferment, and, when the See of Rouen fell vacant, recommended the Pope to place Cauchon on its throne.  The Pope, however, refused his consent, and the Rouen Chapters would hear naught of the Anglicised Bishop.  At that time the Church at Rouen was at war with the University of Paris, and did not wish one of the members of that University placed over it.

Joan of Arc’s place of capture happened to be in the diocese of Beauvais, and although Cauchon was now only nominally Bishop of Beauvais, he still retained that title.  Cauchon now placed himself, body and soul, at the disposal of the English, hoping thereby sooner to obtain the long-coveted Archbishopric of Rouen in exchange for helping his friends to the utmost in his power by furthering their schemes and in ridding them of their prisoner once and for ever.  The bait held out by Winchester and Bedford was the Archbishopric of Rouen, and eagerly did Cauchon seize his prey.  What added to his zeal was his wish to gratify base feelings of revenge on those who had thrust him out of his Bishopric of Beauvais, and on her without whose deeds he might have still been living in security in his palatial home there.

After a consultation with the leaders of the University of Paris, Cauchon arrived at the Burgundian camp before Compiegne on the 14th of July, and claimed Joan of Arc as prisoner from the keeping of the Duke of Burgundy.  Cauchon justified his demand by letters which he had obtained from the doctors of the University, and he made the offer in the name of the child-king of England.  The sum handed over for the purchase of the prisoner was 10,000 livres tournois, equivalent to 61,125 francs of French money of to-day—­about L2400 sterling.  This was the ordinary price in that day for the ransom of any prisoner of high rank.  Luxembourg, to his shame and that of his order, consented to the sale on those terms, and Cauchon soon returned with the news of his bargain to his English employers.