As time passed on, it was found that personal service was the only form of tax that could readily be enforced; and, accordingly, more and more the natives were driven into working the farms of the Spanish settlements. As early as 1496 the fields of the Spaniards had come to be very generally tilled and harvested in this manner. Out of this form of taxation grew the system of _repartimientos_, or _encomiendas_, as they were afterward called. In order to enforce the payment of such tributes as were required, four forts in addition to those of Isabella and St. Thomas were built and equipped, at such points as would give most complete command and control of the island. It requires no very vivid imagination to enable one to understand the desperate situation into which the natives found they had been driven. They had enjoyed a roving independence and that ample leisure which is so dear to all the aboriginal inhabitants of the tropics. This pleasant life was now at an end; the yoke of servitude was fastened upon them, and there was no prospect save in the thraldom of perpetual slavery. They were obliged to bend their bodies under the fervour of a tropical sun, either to raise food for their taskmasters, or to sift the sands of the streams for the shining grains of gold. Peter Martyr relates, with an unspeakable pathos, how their sorrows and sufferings wove themselves into doleful songs and ballads, and how with plaintive tunes and mournful voices they bewailed the servitude into which they had been thrown. At last they determined to avail themselves of a most desperate remedy. They observed how entirely dependent the Spaniards were upon such food as was supplied by the natives. They now agreed, by a general concert of action, not to cultivate the articles of food, and to destroy those already growing, in order by famine to starve the strangers or drive them from the island. This policy was carried into effect. They abandoned their homes, laid waste the fields, and withdrew to the mountains, where they hoped to subsist on roots and herbs. Although this policy produced some distress among the Spaniards, still they had the resources of home; and it is certain that the suffering of the natives even from hunger was far greater than was the suffering of the invaders. The Spaniards pursued the Indians from one retreat to another, following them into caverns, pursuing them into thick forests, and driving them up mountain heights, until, worn out with fatigue and hunger, the wretched creatures gave themselves up without conditions to the mercy of their pursuers. After thousands of them had perished miserably through famine, fatigue, disease, and terror, the survivors abandoned all opposition, and bent their necks despairingly to the yoke.