The Prince did not like this, for he knew that it was partly the truth. He at once offered Du Guesclin his liberty, for a much smaller sum than had been asked before. His council tried to dissuade him from keeping this agreement; but the Prince, speaking like a good and loyal knight, said, "Since we have granted it, we will keep it, and not act in any way contrary."

It was not long before Du Guesclin was able to pay the money, and hastened to join Henry, who was already successfully invading Castile. Most of the towns opened their gates to him, and he defeated Pedro in battle, and pursued him to the fortress of Montiel. Here, by some means or other, Pedro and Henry met face to face. So great was their hatred for one another, that Pedro immediately threw himself upon his brother, and being the stronger, threw him down upon the ground under himself; but Henry managed to draw his long Spanish knife, and plunging it into Pedro, killed him on the spot. After this he was secure in his possession of the throne of Castile, and had no longer to fear any rival.

This event of course entirely destroyed any hopes the Black Prince might still have of getting the money due from Pedro. He had not enough money himself to pay more than half of what was due to the Companies which had fought under his banner. They, on being disbanded, went off to ravage the French territory, which did not tend to make the French feel more friendly to the Black Prince's rule. In truth it is impossible to deny that he showed little talent as an administrator in his position as ruler of Aquitaine.

His subjects were rapidly growing more and more discontented, and many of the chief nobles, who had at first crowded to swear allegiance to him through mere terror of his name, now began secretly to draw near to France. By a fatal mistake of policy he managed to estrange his subjects still further. He was deeply in debt, and had no money either to defray the expenses of his court, or to prepare for a new struggle with France, which he felt must soon be inevitable. He felt, therefore, that it was necessary to impose a tax upon his subjects; and he hit upon the most burdensome tax he could have discovered. He proposed to the Assembly of the States of his Duchy that a hearth tax should be levied for five years; that is, that for every fire upon the hearth an annual duty should be paid. This kind of tax was particularly oppressive, as it fell unequally; the poor pay more in proportion to their small means than do the rich. Hence the tax caused great discontent, especially amongst the Gascon barons, the lords of Armagnac, d'Albret, Cominges, and many others.

The whole duchy seemed to weary of the English rule. The people resented, naturally enough, the ravages and extortions of the Free Companies, and complained that the English nobles were arrogant and overbearing. The King of France watched eagerly this growing discontent; but He remained quiet until he had concluded an offensive and defensive alliance with Henry of Trastamare. The Gascon lords, in their discontent at the new tax, claimed to have a right of appeal to the King of France, as if he had still been the feudal superior of the duchy, to whom the vassals might carry their complaints against their lord. This claim of appeal greatly angered the Black Prince; for in the treaty of Bretigny the King of France had agreed to renounce all rights over Aquitaine, and therefore could receive no appeals. But the Gascons said that it was not in the power of the King of France to renounce these rights without the consent of the barons and cities of Aquitaine; and this consent had never been given, and would never be given. The dispute, as was natural, only increased the ill-will between the Prince and his subjects.

From all sides the King of France was advised to seize this favourable moment for attacking the Prince. He was told that, as soon as he declared war, all the barons and cities of Aquitaine would turn to his side; for all were discontented with the English rule. At last, on the 25th January, 1369, he summoned the Black Prince to appear before the court of his peers at Paris, and answer the complaints brought against him by his vassals. This proceeding was, of course, entirely contrary to the treaty of Bretigny. It was treating the Prince as if he were a vassal of France; whereas, according to the treaty, the King of France had entirely renounced his claim to the allegiance of Aquitaine. By treating the Black Prince as a vassal, he therefore distinctly threw down the gauntlet of war.

Great was the anger of the Prince when this summons reached him. When the commissioners who had brought the letter had read it to him, he looked at them for a moment in silence, and then burst forth in rage.

"We will willingly come to Paris on the day appointed," he said; "but it will be with our helmet on our head, and sixty thousand men at our back."

He would give no other answer to the commissioners; and after they had gone, his anger burnt so hot against them that he sent some of his knights after them, to seize them and bring them back to prison.