Greg,
I was able to find some info that might fit your ancestor. I found three Peter P Lucas's in the record. They were all members of Ohio units.
Nunber one was in the 17th Ohio. That was a three month unit that existed from April of 61 until July of 61.
Number two was a three year unit (the 62nd Ohio) that was organized among other places at Zanesville Ohio. This is a three year unit that was organized between Septemeber and December of 61 Peter P entered this unit as a private and left as a Corporal.
Number three was also a three year unit (67th Ohio) that was organized at large through out the state in October of 61. I don't know what Peter P's rank in was but he was a Corporal when he left the unit in late 1865.
IF I had to take a guess, I would guess that our man was in the 62nd Ohio since it was organized at Zanesville and he was from Zanesville. But then again that is just a guess by me. If you want to obtain his records, you can contact Jim Martin or Alan Pitts by clicking on the "Click here to order Military Records" at the top of the page. There is no guarantee as to what you will get but if there is anything there, they will get it for you.

Frank