Early on the morning of April 25, Confederates blocked the Pine Bluff Road near the Marks family home and mills. The first Union wagons arrived around 9:30 a.m., and the Confederates shot the horses and driver of the lead Union wagon and launched the attack. The battle lasted five hours as the main Southern unit dismounted and charged the wagon train, followed by mounted Missourians charging from the north and mounted Arkansans attacking from the south. The Federal force was sealed as the Confederates first subdued the two lead Union regiments, then the rear guard. The 1st Iowa Veteran Volunteer Cavalry, marching a few miles behind the Union column, formed a line of battle several miles to the west behind Moro Creek, beat off several rebel attacks, and conducted an orderly fighting withdrawal back to Camden. About 1,600 Union troops were engaged against 2,500 Confederates. Union losses could not have been less than 1,300, the majority being captured. Of the 300 unarmed refugee slaves, over 100 were killed by Confederate soldiers. Confederate losses were fewer than 500. The victors captured the entire train, some 1,500 horses and mules, private vehicles, ambulances, four guns, and valuable official reports concerning Steele's army. This loss at Marks' Mills, the previous defeat at Poison Springs, and news that Major General Banks had been defeated in Louisiana prompted General Steele to quickly return to Little Rock. In hasty retreat from Camden through heavy rains, Steele led his Union army into the raging floodwaters of the Saline River and into the final battle of the Red River Campaign at Jenkins' Ferry.