From August 1780 until the following spring, after Col. Francis Marion took control of the Williamsburg Militia, a network of camps where the Great Pee Dee, Little Pee Dee, and Lynches Rivers meet served as a base of operations for his campaign to undermine the British occupation of South Carolina. From this area, Marion attacked vital supply lines between Charleston and Camden and worked to neutralize local loyalist militia forces. Sometime in early 1781, Marion ordered Col. John Ervin, a leader of the Whig militia on Britton’s Neck, to build a redoubt at Dunham’s Bluff. The earthen fortification functioned as a lookout post to monitor traffic on the Great Pee Dee and as a defensive position against light opposition, while a large nearby campsite housed a garrison of militiamen. A generation after the Revolutionary War, South Carolina’s official geographer wrote that control of the rivers allowed Marion to be abundantly supplied with provisions and made his post inaccessible except by water. Although that likely overstated Marion’s strength, it reflected his effort to use the natural environment to his advantage and the strategic importance of the area’s river highways to all sides in the South Carolina Lowcountry conflict.