What were the major causes of war between the Powhatans and the English settlers?

Aside from the cultural differences that contributed to friction between Native peoples and Europeans throughout the Americas, the main cause of the Anglo-Powhatan wars in the years following Jamestown's founding was the desire of English settlers for land. When the Jamestown colonists arrived in Virginia, they entered the empire of the Powhatan people, whose chieftain had spent the previous two decades expanding his influence over the region. At first, he probably saw the English as subject peoples and perhaps valuable allies, but after surviving a series of horrific famines, and nearly failing as a business venture, they began to plant a variety of tobacco that could be easily marketed in Europe. Virginia quickly became a cash crop colony, and the colonists' demands for land increased dramatically. As more and more colonists arrived, they became more of a threat to the Powhatan, and this process led to conflict. The earliest war had actually begun when the Powhatan attempted to starve out the colonists by denying them corn, a response to early English expansion (before tobacco became a factor.) But the introduction of tobacco into the colony sped up expansion and intensified conflict with area natives. This process ended in disaster for the Powhatan.