George A. Brown, age 33, operated a cotton warehouse in Americus GA. He joined the "Sumter Light Guard", which became Co. "K", 4th Georgia Regt., and was discharged for being overage on July 27, 1862.
William H. D. Cook, age 40, worked as an ambrotypist in Talbutton GA.
Charles W. Morgan, age 32, worked as an overseer in Friendship GA.
David Mayo joined the "Sumter Light Guard", which became Co. "K", 4th Georgia Regt. He was discharged, disabled by wounds, July 19, 1862.
http://www.historicalimagebank.com/gallery/main.php/v/album01/album08/4th_GA_Sumter_Lt_Grd.jpg.html
James A. Hill, age 27, operated a farm near Americus GA. He's on the Georgia state census of men available for militia service, January 1864, 884th Militia District of Sumter County. Since there are no other "J" Hills in Sumter on the citizens register mentioned, he's likely your man.
D. A. Mayo appears in the 789th Militia District, age 36, a bricklayer. George A. Brown is also listed there, age 38, a government agent, as well as W. H. D. Cook, age 44, a shoemaker. C. W. Morgan is registered in the 1105th Militia District, age 36, a farmer.
Based on age and occupation, James Hill didn't have an exemption. Perhaps he purchased a substitute or had a physical disability, such as being blind in one eye or having a deformed limb.