Before your Civil War ancestor enlisted in the military and headed off to the battlefield, he lived in a neighborhood. The neighborhood may have been a rural one where it was a mile or so to the next farm, but it was still a neighborhood.
Your ancestor talked with his neighbors, attended church with them and probably celebrated and traded with them. Mapping out who lived near your ancestor may tell you a lot about your own ancestor’s life.
Start by using the online Bureau of Land Management, General Land Office Records. Click on Land Patents. Enter the state and county information for your ancestor. Then enter the township, range and section numbers where he lived. Leave the name section blank. When you click Search Patents you will get a list of people in that section who bought land from the federal government. To find more neighbors, make additional searches on the sections around the one in which your ancestor lived. These people may or may not have lived on the land they bought.
Compare these land ownership records with the 1860 census records. You will probably find some differences. The people in the census may not have owned the land on which they lived.
Now you have a list of names you can use to search for neighbors who served in the military with your ancestor and look for memoirs, newspaper articles and court records that may have involved your ancestor.
If you are interested in creating a map, read Ancestral Archeology: Using Google Maps to Recreate Your Ancestor’s Neighborhood.
Poore Boys In Gray 
The 1860 slave census is also quite telling. I had long known that my ggrandfather’s parents had slaves buried in the back of the family cemetery out in the hills near the Delta (distinguishable by the sunken ground and absence of headstones, but only via the census did I learn how many slaves they had right before the war began.
That famous 9th Mississippi photo has had to do a lot of duty for us, as there are so few others of the Mississippi troops. I keep waiting for some great photo of the 13th to surface, but, alas, I’m still waiting.
I have found the 1860 slave census useful, too. For example, I found that one of my ancestors’ neighbors helped build the railroad that eventually took the Poore Boys to the battlefield. He not only used his own slaves but hired large numbers of other slaves from their owners to help construct the railroad. I wondered how all this activity affected my Poore family and their slaves.