Fortification systems at Double Ditch attest to fierce warfare between villagers and surrounding nomadic tribes reported in early historic records. Ditch 2 appears to have combined mounds and a ditch, with the mounds possibly acting as strong points similar to bastions. An artificial earthen berm inside the ditch rose nearly 10 feet above the ditch floor. Ditch 2 enclosed 12 acres and likely protected 90 to 100 houses. When it was built, the estimated population was around 1,200 persons, making the village one-third smaller than the founding community. Later, extensive earthmoving by site residents destroyed most house features associated with Ditch 2. Fortification systems consisted of a deep moat and a wall of wooden posts that formed a palisade, while natural features such as steep terrain and riverbanks also were used for added protection.