Early European exploration of North America was driven by economic, religious, and curiosity motives. Spain's exploration led by Columbus and later Cortez expanded their empire through conquest of the Aztecs and Incas, aided by disease. France established trading posts under Champlain. England's early colonies at Roanoke and Jamestown struggled until tobacco farming and John Smith's leadership helped Jamestown survive. However, disease devastated native populations and conflict broke out between colonists and groups like the Powhatans. The exchange of goods, plants, animals and diseases between Europeans and natives, known as the Columbian Exchange, profoundly impacted both societies.