I was asked to contribute to an article that recently was released on the FamilySearch Blog, "How to Use FamilySearch’s Civil War Records to Learn about Ancestors."
There are many databases on FamilySearch that are helpful for Civil War era ancestors, but I chose to focus on those that assist in the documentation of a soldier's final resting place.
The article highlights some FamilySearch databases--and they are a good starting point. Just be aware that there are materials beyond FamilySearch that can help with your Civil War ancestor. Pensions are particularly helpful and can provide a wide variety of genealogical information on your ancestor and his family. Service records (see those for Riley Rampley from the 78th Illinois Volunteer Infantry) can provide additional background on your ancestor's service. Those records are at the National Archives.
Don't just limit yourself to finding aids.