Illinois Civil War Muster and Descriptive Rolls Database (Illinois State Archives):
American Civil War Soldiers (ancestry.com)
William Thomas - Pvt - Co I - 18 Illinois Infantry
Civil War Soldiers & Sailors System Search Detail (National Park Service):
William Thomas - Co I - 18 Illinois Infantry
Soldier's rank in - Pvt
Soldier's rank out - Pvt
Film Number M539, Roll 90
Civil War Pension Index (ancestry.com):
Thomas, William H.
Service - I - 18 Ill Inf.
Date of filing - 1889May17 - Invalid; Appl #104664; Ill.
National Graves Registration Database (Sons of Union Veterans of the Civil War):
Thomas, William H. 18 Illinois Infantry
Died, 15Apr1891; Buried, Oakwood, [Joliet] Will County, IL
Will County Illinois USGenWeb Necrologist Reports (© 2002 The ILGenWeb Project All Rights Reserved):
Headstone Reading,Published Obituaries:
Additional Biographical Material: