I have read, in the past, but just re-read the letters and diary/journal of one Leroy Mayfield, lieutenant and later captain of Co. "I" of the 22nd Indiana Infantry. C. H. ("Copernicus H.") Coffey was his cousin. He confirms in the diary that C. H. Coffey and my uncle, Frank, were both killed on June 27th, 1864. The date of June 25th on the marker is incorrect.
In this diary, he also pinpoints the location where my gg-grandfather, John McPike, was wounded at Missionary Ridge and references an injury to J. F. (Frank) Martin at Rome, GA.
This is a terrific diary, if you'd like to read. You can find it at:
http://www.indiana.edu/~imhfiles/Civil_War_VFP/Hoosier_Invades.pdf
This if part of the Indiana Magazine of History, "Voices from the Past; Civil War Soldiers' Letters and Diaries" at
http://www.indiana.edu/~imaghist/online_content/vcsfrmpst/voices_cvlwr/index.html
If I plan another trip and have some time, I'll contact you.
Jim