Johnny, don't waste your time on all those W. Mobley's. I have all of them in my database -- none of them were from Pike County, and all of them were older than your William M. Mobley. Due to the young age of your ancestor, he would have served fairly late in the war, and few service records from that period can be found. At any rate, there's no record of his service in any Arkansas regiment, although it's possible he served in Newton's 10th Regiment Arkansas State Troops.