103rd Regiment, Ohio Infantry

Brief History
The 103rd Regiment was organized at Cleveland, Ohio, August, 1862. It had duty at Raleigh, North Carolina, and in the Department of North Carolina until June. The regiment mustered out June 12, 1865.

The Wikipedia article, 103rd Ohio Infantry, has history for this regiment and additional sources.

Companies in the 103rd Regiment with the County of Origin
Men often enlisted in a company recruited in the counties where they lived though not always. After many battles, companies might be combined because so many men were killed or wounded. However if you are unsure which company your ancestor was in, try the company recruited in his county first.

Source Material
Internet site, 103rd Ohio Infantry, by Larry Stevens has brief histories and references for this regiment.