A Confederate reenactor can show the most individuality with his hat. By mid-war there were almost as many different looking hats as there were soldiers in the Confederate army. Early in the war, forage caps, and to a lesser extent, kepis were in use among the militia. However, as the war dragged on, practicality overrode military vanity. A slouch hat with a wide brim kept the sun off in the summer and the rain off in the winter (although some would say it is harder to keep on your head in a stiff wind than a cap!) When they could get it, soliders sometimes adorned their hats with brass insignia indicative of their regiment or home state and occasionally turned up the brim on one side for a jauntier look.
If you get a forage cap, you can get one to match the rest of your uniform (although having everything match is probably not very representative of the majority of soldiers) or you can select any of a number of wool colors. If you go with a slouch hat, you can buy it unshaped - it comes with a high crown in the shape of a dome. You then wet it thoroughly and shape it to your taste. Note that drying a wool hat with heat (or throwing it in the back of a car in the sun on a hot day) will shrink it.
If you are a sometime-Federal, you can get a simple, black civilian slouch that will do for both - however, you may want to purchase a separate forage cap in dark blue wool for your Federal impression.
C & D Jarnigan & Co. (2000 prices)
#5004 Confederate Slouch Hat
(black, tan, or gray)
$42.95 #913 Forage Cap (regular wool) $34.95 #913 Forage Cap (jean wool) $36.95
If you want to spend a bit more, you can order a hat that is an exact replica of an original (as depicted in the Time-Life book series, Echoes of Glory.) Tim Allen is considered by many to be the best at these - but you'll pay extra. Tim's hats ranged from $70 to $100 on his 1998 price list.
Tim Allen Hats
1429 Becket Rd.
Eldersburg, MD 21784