Familysearch.org/ continues to be amazing with the number of databases they continue to upload. Three and a half billion records so far. With Memorial Day coming up, many of the PAID genealogy sites offer limited free access to veterans' records. But FamilySearch has many of those same records available for free 24/7. Or they might link to ancestry.com/ (a paid site) with whom they recently partnered on some databases. Curious about your Civil War ancestors? Familysearch has made it easier to locate their military docs.
"There are a lot of Civil War-related collections that don't say 'Civil War' on them," FamilySearch spokesman Paul Nauta said. The average person won't think to look at those. We've aggregated all these collections together online so a novice can go and see the broad spectrum of selections to see if they can find their ancestors."
Have a look at FamilySearch's database and its wiki article below. Don't know your ancestors' names? If you know your grandparents' full names and/or the names of your great-grands, you can trace backwards via the U.S. Census. Holler at me for more.
https://familysearch.org/civil-war#wiki_articles