With regard to his personal qualities, he was courteous, affable, engaging eloquent; full of insinuation and address; inexhaustible in his resources; active and enterprising.

But these splendid accomplishments were attended with such defects as rendered them pernicious to his country, and even ruinous to himself: he was volatile, inconstant, faithless, revengeful, malicious; restrained by no principle or duty; insatiable in his pretensions: and whether successful or unfortunate in one enterprise he immediately undertook another, in which he was never deterred from employing the most criminal and most dishonorable expedients.
The constable of Eu, who had been taken prisoner by Edward at Caen, recovered his liberty, on the promise of delivering, as his ransom, the town of Guisnes, near Calais of which he was superior lord: but as John was offended at this stipulation, which, if fulfilled, opened still farther that frontier to the enemy, and as he suspected the constable of more dangerous connections with the king of England, he ordered him to be seized, and without any legal or formal trial, put him to death, in prison.

Charles de la Cerda was appointed constable in his place; and had a like fatal end: the king of Navarre ordered him to be assassinated; and such was the weakness of the crown, that this prince, instead of dreading punishment, would not even agree to ask pardon for his offence, but on condition that he should receive an accession of territory: and he had also John's second son put into his hands, as a security for his person, when he came to court, and performed this act of mock penitence and humiliation before his sovereign.[*] * Froissard, liv.i.chap.

144.
{1355.} The two French princes seemed entirely reconciled; but this dissimulation, to which John submitted from necessity, and Charles from habit, did not long continue; and the king of Navarre knew that he had reason to apprehend the most severe vengeance for the many crimes and treasons which he had already committed, and the still greater, which he was meditating.

To insure himself of protection, he entered into a secret correspondence with England, by means of Henry, earl of Derby, now earl of Lancaster, who at that time was employed in fruitless negotiations for peace at Avignon, under the mediation of the pope.