Poison Springs Battleground State Park preserves part of the site of the Battle of Poison Spring in Ouachita County, Arkansas, fought on April 18, 1864, during the Camden Expedition. There Confederate forces and Choctaw Indians overran a Union supply wagon train, a defeat that helped hasten the expedition’s failure. The battle became especially infamous for the killing of Black Union soldiers from Kansas, as no prisoners were taken. Although the present park covers only about 85 acres, the fighting spread across more than 9,000 acres, much of whose landscape still resembles its wartime appearance. The site is also recognized on the National Register of Historic Places and within the Camden Expedition Sites National Historic Landmark.