During the war the Marechal nevertheless took several of the Duke's fortresses in Brescia; but a perfect understanding had been established between them which rendered this circumstance comparatively unimportant; and on the refusal of Henry to permit the appointment of a governor of his own selection for the citadel of Bourg, Biron became so incensed by what he designated as the ingratitude of his sovereign--though he was fully aware that by countenancing such an arrangement the King must necessarily leave the fortress entirely in his power--that he no longer restrained himself, but declared that the death of the French sovereign was essential to the accomplishment of his projects; and meanwhile he gave the Duke of Savoy, whom he thenceforward regarded as his firmest friend, constant information of the state and movements of the hostile army.
A short time afterwards it was definitely arranged between the conspirators that the Duke of Savoy should give his third daughter in marriage to the Marechal, with a dowry of five hundred thousand golden crowns; that the Spanish monarch should cede to him all his claims of sovereignty upon the duchy of Burgundy; and that the Conde de Fuentes[178] and the Duke of Savoy should march their combined forces into France, thus disabling Henry from pursuing his design of reconquering the long-coveted duchy.
This treasonable design, owing to circumstances upon which the impetuous Biron had failed to calculate, proved, however, abortive; and he had no sooner convinced himself of the fact, and comprehended the perilous position in which he had been placed by his imprudence, than he hastened to Lyons, where the King was then sojourning; and having obtained an audience, he confessed with a seeming frankness irresistible to so generous and unsuspicious a nature as that of Henry, that he had been sufficiently misled by his ambition secretly to demand from the Duke of Savoy the hand of his younger daughter; and that, moreover, in the excess of his mortification at the refusal of his Majesty to appoint a governor of his own selection at Bourg, he had even been induced to plot against the state, for both which crimes he humbly solicited the royal pardon.
Full well did Henry and his minister remember this occurrence; nor could the King forget that although he had urged the Marechal to reveal to him the whole extent of the intrigue, he had dexterously evaded his most searching inquiries, and constantly recurred to his contrition.

Henry owed much to Biron, whom he had long loved; and with a magnanimity worthy of his noble nature, after a few expostulations and reproaches, he not only pardoned him for what he believed to have been a mere temporary abandonment of his duties, but even assured him of his future favour, and bade him return in all security to his post.
Unhappily, however, the demon of ambition by which the Duke was possessed proved too powerful for the generous clemency of the King, and he resumed his treasonable practices; but a misunderstanding having ensued between himself and the false friend by whom he was now betrayed, all the private documents which had been exchanged between himself and the foreign princes through whose aid he trusted to obtain the honours of sovereignty, were communicated on this occasion to the monarch whose dignity and whose confidence he had alike outraged.
A free pardon was accorded to the traitor through whose means Henry was made acquainted with the extent of the intrigue, on condition that he should reside within the precincts of the Court and lend his assistance to convict the Duke of his crime, terms to which the perfidious confidant readily consented; while with a tact worthy of his falsehood, he soon succeeded in reinstating himself in the good graces of the Duke, by professing to be earnestly engaged in France in furthering his interests, and by giving him reason to believe that he was still devoted to his cause.
To this deception, and to his own obstinacy, Biron owed his fate.[179] The alarming facts which had thus been revealed to them were communicated by Henry and his minister to certain members of the privy council, by whom a report was drawn up and placed in the hands of the Chancellor; and, this preliminary arrangement completed, it was determined to recall the Marechal to Court either to justify himself, or to undergo the penalty of his treason.

In order to effect this object, however, it was necessary to exercise the greatest caution, as Biron was then in Burgundy; and his alarm having already been excited by the evasion of his most confidential agent, they felt that he might, should his suspicions be increased, place himself at the head of the troops under his command, by whom he was idolized, and thus become doubly dangerous.

It was, consequently, only by a subterfuge that there was any prospect of inducing him to approach the capital; and the King, by the advice of Sully, and not without a latent hope that he might be enabled to clear himself of blame, openly asserted that he put no faith in the disclosures which had been made to him, and that he would advise the Marechal to be careful of those about him, whose envy or enmity led them to put a misconstruction upon his motives as well as upon his actions.
The Baron de Luz,[180] the confidential friend of Biron, for whose ear these declarations were especially designed, did not fail to communicate them on the instant to the accused party; while La Fin,[181] by whom he had been betrayed, likewise wrote to assure him that in revealing the conspiracy to the King and the ministers he had been cautious not to utter a word by which he could be personally implicated.

It is certain, however, that the Duke placed little reliance either upon the assertions of Henry, or the assurances of his treacherous agent; as on the receipt of a letter from the sovereign, announcing his own instant departure for Poitou, where he invited Biron to join him, in order that he might afford him his advice upon certain affairs of moment, the latter wrote to excuse himself, alleging, as a pretext for his disobedience to the royal command, the rumour of a reported aggression of the Spaniards, and the necessity of his presence at a meeting of the States of Burgundy which had been convoked for the 22d of May, where it would be essential that he should watch over the interests of his Majesty.[182] The King did not further insist at that moment; but having ascertained on his return from Poitou that fresh movements had been made in Burgundy, in Saintonge, in Perigord, and in Guienne, which threatened to prove inimical to his authority, and that couriers were constantly passing from one of these provinces to the other, he sent to desire the presence of the Sieur Descures,[183] an intimate friend and follower of the Marechal, whom he commanded to proceed with all speed to Burgundy, and to inform his lord that if he did not forthwith obey the royal summons, the sovereign would go in person to bring him thence.