I'm trying to understand why my great-grandfather's brother died while in service during the Civil War. Here are his stats:

Name: William T Johnson
Rank: Private
State: Illinois, Union
Unit, Company, Whateveritscalled: I Battery, 1st Light Artillery
Mustered In: 2 Mar 1862
Died: 17 Jul 1862 in Moscow, Tennessee

I have not been able to find any record of a skirmish in the vicinity of Moscow, Tennessee, on or around that date. Of course I realize that there could be a number of reasons he died, including some kind of accident or disease. I can find his record at the Illinois archieves, but the cause of death is not listed. I know the death date & location is correct because it matches what was recorded in the Johnson Family Bible by his father.

According to my research 1 man was killed & 13 men died of disease. So this isn't a staggering number of records to investigate to determine which applies to my soldier. Where could I find these records, if they even exist? I just don't know what direction to look next.

Thanks for any tips anyone might care to provide!