Tom,
I have researched, along with Neil Block and others, for the names of the Union soldiers killed at Centralia and this is the info I have on your ancestor. The bio is from his service record and findagrave.com for his burial.
E. D.
edwilson10@comcast.net
THOMAS, James W(1) Pvt Co A-B, 1st Missouri Engineers. Enlisted Aug 29, 1862 St Joseph, MO with Co D, 25th Missouri Infantry Age 27 5’9” Dark complexion, blue eyes, dark hair , Native of MO, occupation farmer. Buried Fee Fee Cemetery, Bridgeton, MO.
(1) http://www.findagrave.com/cgi-bin/fg.cgi?page=gr&GSln=thomas&GSbyrel=in&GSdy=1864&GSdyrel=in&GSst=26&GScntry=4&GSob=n&GRid=35917840&