 Complete the following phrase:  The 21st Texas Cavalry saw action in the Trans-Mississippi Theater. As a lieutet, Walton led scouting raids in the vicinity of Helena, Arkansas. In the spring of 1863, he commanded Maj. Gen. John S. Marmadukes vanguard in the Battle of Cape Girardeau. Walton was later promoted to major and attached to the staff of Lt. Gen. Theophilus H. Holmes, commander of the Trans-Mississippi Department, and stationed at Little Rock, Arkansas. After the Battle of Helena and the Confederate evacuation of Little Rock, Walton took part in the Red River Campaign, leading a company in the battles of 