Originally, the supposed right of condemning captives to death rendered the reducing of them to perpetual slavery an act of mercy on the part of the conqueror, which practice was not entirely exploded even in the fourteenth century, when Louis Hutin in a letter to Edward II. his vassal and ally, desired him to arrest his enemies, the Flemings, and make them slaves and serfs. (_Mettre par deveres vous, si comme forfain à vous Sers et Esclaves à tous jours._) _Rymer._ Booty, however, being equally with vengeance the cause of war, men were not unwilling to accept of advantages more convenient and useful than the services of a prisoner; whose maintenance might be perhaps a burden to them, and to whose death they were indifferent. For this reason even the most sanguinary nations condescended at last to accept of ransom for their captives; and during the period between the eleventh and fifteenth centuries, fixed and general rules appear to have been established for the regulating such transactions. The principal of these seem to have been, the right of the captor to the persons of his prisoners, though in some cases the king claimed the prerogative of either restoring them to liberty, or of retaining them himself, at a price much inferior to what their original possessor had expected. On a similar principle, Henry IV. forbade the Percies to ransom their prisoners taken at Holmdown. In this case the captives consisted of the chief Scottish nobility, and the king in retaining them, had probably views of policy, which looked to objects far beyond the mere advantage of their ransom. It is mentioned by a French antiquary that the King of France had the privilege of purchasing any prisoner from his conqueror, on the payment of 10,000 livres; and as a confirmation of this, the money paid to Denis de Morbec for his captive John, King of France, by Edward III. amounted to this exact sum. The English monarch afterwards extorted the enormous ransom of three millions of gold crowns, amounting, as it has been calculated, to £1,500,000. of our present money, from his royal captive. The French author censures Edward somewhat unjustly for his share in this transaction; here as in the case of the Percies, state reasons interfered with private advantages. John yielded up to his conquerors not only the abovementioned sum, but whole towns and provinces became the property of the English nation; to these De Morbec could have no right. It was, however, notwithstanding the frequent mention in history of ransoms, still in the power of the persons in possession of a prisoner to refuse any advantage, however great, which his liberty might offer them, if dictated by motives of policy, dependant principally on his personal importance. Entius, King of Sardinia, son of Frederic II. was esteemed of such consequence to his father's affairs, that the Bolognese, to whom he became a prisoner in 1248, would accept of no