He was also so thorough a diplomatist that it was commonly remarked that it was more difficult to penetrate his designs than the fastnesses of his duchy.

He died at Savillan on the 26th of July 1630.
[81] Charles de Gontault, Due de Biron, Peer, Admiral, and Marshal of France, acquired great reputation alike for his valour and his services.
He was honoured with the confidence of Henri IV, who created the barony of Biron into a duchy-peerage for his benefit, and loaded him with proofs of his favour; Biron, however, repaid his sovereign with the basest ingratitude by entering into a treaty with the Duke of Savoy and the Spaniards, who were both inimical to France.

Having refused to acknowledge his fault, and thereby exhausted the forbearance of the King, he was put upon his trial, convicted of the crime of _lese-majeste,_ and condemned to lose his head.

The sentence was carried into execution in the court of the Bastille on the 31st of July 1602.
[82] Guichenon, _Histoire de Savoie_.
[83] Daniel, _Histoire de France_, vol.vii.p.

386.
[84] L'Etoile, _Journal de Henri IV_, vol.ii.p.