One source could include the use of diaries and journals from that time period.  In some cases, average to poorly educated people wrote (and spelled) in the same manner that they spoke, much as people tend to do today.  Taking these sources from appropriate the appropriate regions may give you some clues.  Also, if you look at the country of origin that the person or their family came from, and the amount of time that the family or person was in the country, you might find additional ideas on that particular person's accent.

----Original Message Follows----
From: Cate Poole <[log in to unmask]>
Reply-To: Museum discussion list <[log in to unmask]>
To: [log in to unmask]
Subject: Civil War Accent for Actor
Date: Thu, 29 May 2003 11:05:25 -0400
I am doing research for a Civil War soldier character for a video script. When I started to write
the dialogue, I realized that the conversational speech I was using was coming from my 2003
interpretation. Could anyone recommend a source where I could find out about how people
spoke during the Civil War. I am especially interested in everyday speech and accents as they
relate to geographic locations. Any recommendations are appreciated.
Cate
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