In early 1862, Ross returned to duty. By late February, 500 troops and he were assigned to raid the Union Army. He led the group behind the enemy lines, to Keetsville (now Washburn), Missouri, where they gathered intelligence, destroyed several wagonloads of commissary supplies, captured 60 horses and mules, and took 11 prisoners. The following month, the regiment was assigned to Earl Van Dorn, now a major general, with whom Ross had served during the battle at the Wichita Village. Under Van Dorn, the group suffered a defeat at the Battle of Pea Ridge; Ross attributed their loss solely to Van Dorn, and blamed him for overmarching and underfeeding his troops, and for failing to properly coordinate the plan of attack. In April, the group was sent to Des Arc, Arkansas. Because of the scarcity of forage, Ross's cavalry troop was ordered to dismount and send their horses back to Texas. The unit, now on foot, traveled to Memphis, Tennessee, arriving two weeks after the Battle of Shiloh. Ross soon caught a bad cold accompanied by a lingering fever, and was extremely ill for eight weeks. By the time he considered himself cured, his weight had dwindled to only 125 lb (57 kg).