April 18, 1864. Marmaduke attacked and destroyed a Union supply train returning to Camden at Poison Spring.

The Union Army reached Camden on April 15, 1864, in search of supplies, and they were soon disappointed at how little they found to feed thousands of hungry soldiers and their equally hungry horses and mules. On the 17th of April, General Steele sent out an expedition to forage for supplies of corn reputed to be in the White Oak Creek area about eighteen miles from Camden. The force included over 600 hundred soldiers under the command of Col. James M. Williams, along with 198 wagons and four cannons. They foraged the area gathering remaining supplies of corn and other plunder from farms and plantations before regrouping at White Oak Creek. An additional force of five hundred men, including cavalry and infantry and two pieces of artillery, joined Col. Williams' force the next day. The combined Union forces of some 1,100 found themselves facing 3,600 Confederate soldiers under the command of Brig. General John Sappington Marmaduke and Brig. General Samuel B. Maxey who were blocking the road to Camden. Fighting ensued in a series of attacks with the Union troops retreating after the third attack. The Confederate cavalry pursued retreating Union forces for two and a half miles before breaking off pursuit and turning their attention to the Union wounded and prisoners of war. The Battle at Poison Spring became notorious for the killing and mutilation of wounded and captured Black troops in this engagement after the battle had ceased.

Union losses were 301 men killed, wounded or missing. The majority of those killed or wounded were colored troops from the First Kansas Colored with 117 dead and 65 wounded. The First Kansas Colored had been made up of former slaves and free persons of color from Arkansas and Missouri. Some Union officers had at first doubted the potential of Black troops, but the First Kansas Colored had performed well at the Battle of Honey Springs in Indian Territory in July 1863. Honey Springs was the largest Civil War battle in Indian Territory, now Oklahoma, and involved Indian troops on both sides as well as the First Kansas Colored on the Union side. It was a Union victory. Col. Tandy Walker's Choctaw Confederate troops were at Poison Spring and were perhaps eager to repay that earlier loss. Confederate losses at Poison Spring are not known exactly but were probably somewhere between 114 and 145.

Numerous monuments, markers and signage from different eras are at the Poison Spring State Park. The oldest is the stone monument placed on the site by the Camden UDC in 1929. It is followed by a stone monument from the 1936 Centennial of Arkansas statehood. A metal marker dates from the 1964 Centennial of the Civil War from 1961-65. A more recent sign notes that Poison Spring is one of the Camden Expedition National Historic Landmarks, sites of national consequence. Other markers under the pavilion give details on the forces and the battle. There are picnic tables for visitors and a short hiking trail. Re-enactments take place every two years with Confederate and Union re-enactors from the region and re-enactors of the First Kansas Colored troops from nearby Camden.

This brings us to our next point of interest, Camden.

Here is a web page with more information:
Encyclopedia of Arkansas