What induced Berkeley to take this strange step none could tell. The murders of the savages were continuing. The frontier was defenseless. Messages were coming from the exposed plantations imploring aid. Why should he desert the people and expose them to the fury of the Indians? It is possible that he detected symptoms of mutiny among the troops and thought it better to abandon the expedition than to run the risk of a rebellion. He was well aware of the discontent of the people, and his letters to England show that he dreaded an insurrection.[493] The unhappy planters ascribed the Governor's strange conduct to avarice. He and his friends had a monopoly of the Indian trade, and it was hinted that he preferred to allow the atrocities to continue rather than destroy his source of revenue. He was determined, was the cry, "that no bullits would pierce beaver skins".[494] More probable seems the explanation that Berkeley hoped to prevent further depredations by the help of the Pamunkeys and other friendly tribes, and feared that an invasion of the Indian lands might defeat this purpose.[495] But an Assembly was summoned in March and instructed by the Governor to take immediate measures to secure the frontier.[496] Acting, no doubt, under Berkeley's influence, the Assembly resolved not to carry the conflict into the enemy's territory, but to wage a defensive war. Forts were to be erected upon the upper waters of the great rivers, and manned with regular troops as a protection to the outer plantations. To defray the cost, new and heavy taxes were put upon the people.[497] This last act of the Long Assembly caused bitter dissatisfaction. The border counties had hoped that provision would be made for an expedition against the Indians. No headway could be made unless the whites took the offensive and hunted down the savages in their own villages. The erection of forts was useless.[498] The Indians would experience no difficulty in avoiding them in their murderous raids. They could approach the remote plantations, or even those far within the frontiers, without fear of detection by the soldiers, for the numerous swamps and dense woods afforded them ample covert. It was not intended that the forts should be used as bases for expeditions into the enemy's country; nor could the soldiers leave them to pursue and punish the plundering savages. What then, it was asked, could be the value of fortresses, if they were to defend only the ground upon which they stood?[499]