What Is The Easiest Way To Find My Civil War Union Or Confederate Ancestor?

Though there are now many sites that list those who served in the Union and Confederate forces, one of the easiest ways to access this information is through the National Park Service at Gettysburg, Pennsylvania. 

Your family member(s) did not have to had fought at Gettysburg in order to be listed in this database.

With a bit of information, you can access  https://www.nps.gov/gett/learn/historyculture/ancestor-search.htm
and discover a number of interesting facts about your ancestor.