He sent re-enforcements to the Prince of Wales, whose brother, the Duke of Lancaster, landed with an army at Calais; and he offered to all the adventurers with whom Europe was teeming possession of all the fiefs they could conquer in France.
Charles V.on his side vigorously pushed forward his preparations; he had begun them before he showed his teeth, for as early as the 19th of July, 1368, he had sent into Spain ambassadors with orders to conclude an alliance with Henry of Transtamare against the King of England and his son, whom he called "the Duke of Aquitaine." On the 12th of April, 1369, he signed the treaty which, by a contract of marriage between his brother, Philip the Bold, Duke of Burgundy, and the Princess Marguerite of Flanders, transferred the latter rich province to the House of France.
Lastly he summoned to Paris Du Guesclin, who since the recovery of his freedom had been fighting at one time in Spain, and at another in the south of France, and announced to him his intention of making him constable.

"Dear sir and noble king," said the honest and modest Breton, "I do pray you to have me excused; I am a poor knight and petty bachelor.
The office of constable is so grand and noble that he who would well discharge it should have had long previous practice and command, and rather over the great than the small.

Here are my lords your brothers, your nephews, and your cousins, who will have charge of men-at-arms in the armies, and the rides afield, and how durst I lay commands on them?
In sooth, sir, jealousies be so strong that I cannot well but be afeard of them.

I do affectionately pray you to dispense with me, and to confer it upon another who will more willingly take it than I, and will know better how to fill it." "Sir Bertrand, Sir Bertrand," answered the king, "do not excuse yourself after this fashion; I have nor brother, nor cousin, nor nephew, nor count, nor baron in my kingdom, who would not obey you; and if any should do otherwise, he would anger me so that he would hear of it.

Take, therefore, the office with a good heart, I do beseech you." Sir Bertrand saw well, says Froissart, "that his excuses were of no avail, and finally he assented to the king's opinion; but it was not without a struggle, and to his great disgust.