The irritation which he felt under this complicated disappointment, combined with the consciousness that he had been duped by the Cardinal, and compelled to act as the subordinate of an individual so inferior to himself in rank, created a disgust which, carefully as he endeavoured to conceal it, soon became evident to those about him; nor was it long ere Marie de Medicis and Monsieur were informed of his disaffection. Confidential messengers were immediately despatched to invite the Duke to espouse their cause, and they found a powerful ally in the Duchess, Maria Felicia d’Ursini, who was a near relative of the Queen-mother.
Weary of inaction, anxious for revenge, and, perhaps, desirous of emulating the generous example of the Duc d’Epernon, who had previously declared himself the champion of Marie, Montmorency was at length prevailed upon to consent to their solicitations, and even to pledge himself to receive Gaston in Languedoc; although at the same time he urged him not to quit Brussels until the end of August, in order that he might have time to complete the necessary preparations.
The prospect of possessing so powerful an ally strengthened the hopes of the royal exiles; and immediately upon the arrival of Monsieur in the Low Countries, the mother and son began to concert measures for the success of their difficult and dangerous undertaking. The first impediment which they were called upon to surmount was their total inability to defray the expenses of a powerful army, and to secure the necessary funds for maintaining a secret correspondence with their French adherents. The munificence of Isabella supplied all their personal wants, but even her truly regal profusion could not be expected to extend beyond this point; and it was ultimately agreed that both parties should forward at all risks their jewels by a trusty messenger to Amsterdam for sale.