Neither Richelieu nor De Luynes were deceived as to the feeling which thus induced them to make common cause.  There was no affectation of regard or confidence on either side; their mutual hatred was matter of notoriety, but they were essential to each other.  Without the aid of the favourite, the Bishop of Lucon could never hope to attain the seat in the Conclave which was the paramount object of his ambition; while De Luynes, on his side, was apprehensive that should the army of the King be defeated, his own overthrow must necessarily result, or that, in the event of success, the Prince de Conde would become all-powerful:  an alternative which presented the same danger to his own prospects.  Thus both the one and the other, convinced that by stratagem alone they could carry out their personal views, eagerly entered into a secret negotiation, which terminated in a pledge that Richelieu should succeed to a cardinalate provided he delivered up his too confiding mistress to the royal troops when they marched upon the Fonts de Ce.

This fortress, which protected the passage to Anjou, was only a league distant from Angers, where the Queen-mother had taken up her residence; and Richelieu, to whom its safety had been confided, no sooner effected a final understanding with De Luynes than he removed all the ammunition from the fortress, and placed his own relatives and friends in command of the garrison, with full instructions as to the part which they were to enact when confronted with the troops of the sovereign.

Although wholly unsuspicious of the treachery of which she was thus destined to become the victim, the alarm of the Queen-mother was excited by the rapid approach of her son, and she at length resolved to attempt a tardy reconciliation; for which purpose she despatched the Duc de Bellegarde, the Archbishop of Sens, and the Jesuit Berulle to the King with an offer to that effect.  Louis received her envoys with great courtesy, and declared himself ready to make every concession as regarded Marie personally, and even to extend his pardon to the Comte and Comtesse de Soissons; but he peremptorily refused to include the other disaffected nobles in the amnesty; when the Queen, on her side, declined every arrangement which involved the abandonment of her followers; and thus the negotiation failed in its object, while the royal army continued to advance.[54]

On reaching La Fleche the King convened a council, at which it was proposed to besiege the city of Angers; but Louis, who was aware of the plot that had been formed between De Luynes and Richelieu, declared that his respect for his mother would not permit him to attack a town in which she had taken up her abode; while he even instructed the Duc de Bellegarde to propose to her fresh conditions of peace, and to assure her that his intention in approaching so near to her stronghold was simply to secure an interview, and to induce her to return with him to the capital.