The earlier wars did not involve remote or prolonged campaigns, and they were waged by levies of the common people. But war brought in a new source of possessions, plunder, and a new social factor, the captive. In the earlier, simpler days of war, the captive man was kept only to be tortured or sacrificed to the victorious god; the captive women and children were assimilated into the tribe. But later many captives were spared to be slaves because they had exceptional gifts or peculiar arts. It would be the kings and captains who would take these slaves at first, and it would speedily become apparent to them that these men were much more their own than were the peasant cultivators and common men of their own race.[149] The slave could be commanded to do all sorts of things for his master that the quasi-free common man would not do so willingly because of his attachment to his own patch of cultivation. From a very early period the artificer was often a household slave, and the manufacture of trade goods, pottery, textiles, metal ware, and so forth, such as went on vigorously in the household city of the Minos of Cnossos, was probably a slave industry from the beginning. Sayce, in his _Babylonians and Assyrians_,[150] quotes Babylonian agreements for the teaching of trades to slaves, and dealing with the exploitation of slave products. Slaves produced slave children, enslavement in discharge of debts added to the slave population; it is probable that as the cities grew larger, a larger part of the new population consisted of these slave artificers and slave servants in the large households. They were by no means abject slaves; in later Babylon their lives and property were protected by elaborate laws. Nor were they all outlanders. Parents might sell their children into slavery, and brothers their orphan sisters. Free men who had no means of livelihood would even sell themselves into slavery. And slavery was the fate of the insolvent debtor. Craft apprenticeship, again, was a sort of fixed-term slavery. Out of the slave population, by a converse process, arose the freed-man and freed-woman, who worked for wages and had still more definite individual rights. Since in Babylon slaves could themselves own property, many slaves saved up and bought themselves. Probably the town slave was often better off and practically as free as the cultivator of the soil, and as the rural population increased, its sons and daughters came to mix with and swell the growing ranks of artificers, some bound, some free.