Civil War in Arkansas

In the 1990s I was able to go online and find long lists of soldiers who fought in the Civil War. I am looking for a website that will allow me to do that again. My ggreatgrandfather was John M. Harris, b. 1835 in Missouri and then lived in Arkansas, was killed during the War. Can anyone lead me to these sites as I would like to find out when he died, where he is buried, etc. Thank you so much. Any information will be greatly appreciated.