One advantage of Jamestown was that its location was far enough up the James River that it was easily defended from attack from Spanish ships. Spanish attacks had ravaged English settlements before, and Jamestown was intended in part to serve as a strategic barrier to Spanish expansion up the east coast. So this was a real advantage. Another advantage, though one not immediately evident, was the suitability of the local climate and soils for cultivating tobacco, which became a staple crop of the colony a little over ten years after the initial settlement. The list of disadvantages was far longer. The location of the settlement lacked a consistent supply of fresh water, being in the tidal region of the James River. It was also low-lying, which meant that the colonists were constantly exposed to disease-bearing mosquitos. Moreover, it was squarely in the middle of a region dominated by the powerful Powhatan Confederacy. While the colonists maintained friendly relations with these Indian peoples, they proved to be valuable allies. When the colonists did not, they were tough and implacable enemies. Finally, the colony's location did not allow the English colonists to duplicate what the Spanish had done in South and Central America. It lacked the precious metals that the English hoped to discover, and they were forced to come up with a new plan for colonization that only really worked out in the long run, and after many deaths.