Chalais likewise kept his counsel, and the conspirators appear to have entertained no suspicion that they had a traitor in their midst, and probably attributed the Fleury fiasco to some vague warning furnished the Cardinal by one or other of the many secret agents whom he had in his pay. Had Chalais promptly avowed his enforced betrayal of their designs, they would certainly have proceeded with a great deal more caution, even if they had not decided to abandon the enterprise altogether. But, for a while, he appears to have been of opinion that his wisest course was to say nothing to his friends, and to keep, at least to some extent, his promise to report any fresh developments to the Cardinal; and when at length his secret was forced from him by the address of Madame de Chevreuse and he was involved anew in the conspiracy, its leaders were already hopelessly compromised. Whether by Chalais or by one of his secret agents, Richelieu’s attention was directed to the Duc de Vendôme, whose movements he caused to be closely watched. Vendôme had resolved to offer _Monsieur_ an asylum in his government of Brittany, and the Cardinal ascertained that he was secretly preparing for war, and that he was in communication with the authorities of La Rochelle. Recognising the importance of stifling at its birth the insurrection in a great province so close to La Rochelle and so exposed to an English invasion, he persuaded the King to proceed thither in person to re-establish his threatened authority. But, since he was doubtful if his Majesty could be brought to consent to the arrest of his half-brothers, the duke and Grand Prior, he resolved to ascertain how far he was prepared to support him, and accordingly requested permission to retire, on the ground of failing health. Louis declined his resignation in a letter which was equivalent to an oath of fidelity from the King to his Minister, and concluded with these words: “Be assured that I shall never change, and that, whoever may attack you, you shall have me for second.” Armed with this promise, Richelieu no longer hesitated to represent to the King the necessity of arresting the natural sons of Henri IV, and Louis at once assented. On learning of the approach of the Court, the Duc de Vendôme, who was at Nantes, became very uneasy; but since he could not abstain from paying his homage to his sovereign without practically proclaiming himself a rebel, he charged his brother the Grand Prior to obtain an assurance of safety from the King. “I give you my word,” said Louis, “that he will come to no more harm than you.” Deceived by this gross equivocation, the duke joined the Court at Blois, where it had arrived on June 6, and was very graciously received. But, two days later, both he and his brother were arrested in their beds by Du Hallier, Captain of the Guards, and conducted to the Château of Amboise, where they were very strictly guarded (June 12).