On May 14 1607, a group of around 100 English men arrived in Virginia to establish a permanent colony. They landed first at Cape Henry but, needing a more secure location, set up camp on a peninsula that was connected to the mainland. They named this river after their king, James I, and the Jamestown colony was thus established.
The main advantage of this river location was practical: the water was deep enough to allow ships to dock at the riverbank, thereby eliminating the need to have a number of smaller ships to ferry supplies to the camp. There were tactical advantages too: the camp was nestled so far up the river that potential enemies wouldn't launch a direct attack, for fear of being spotted too early. This was comforting to know when the French, Spanish and Dutch were all in close proximity.
But siting the camp on the River James also had its disadvantages. There were no fresh water springs in this area (which explains why the Native Indians had never settled there) and, as a result, the water was very brackish and not suitable for drinking. Swampy and marshy land also brought large numbers of mosquitoes. These conditions created serious health problems for the settlers: between 1609-1610, over 80 percent of the people at Jamestown had perished.