12th Regiment, Virginia Infantry (Confederate)
12th Regiment, Virginia Infantry was organized at Norfolk, Virginia, in May, 1861, using the 4th Battalion Virginia Volunteers as its nucleus. Its members were from Petersburg, Richmond, Hicksford, and Norfolk.
Of the 348 engaged at Gettysburg, only four percent were disabled. It surrendered 12 officers and 177 men. The field officers were Colonels Everard M. Feild and David A. Weisiger; Lieutenant Colonels John R. Lewellen and Fielding L. Taylor; and Majors Edgar L. Brockett, Richard W. Jones, and John P. May. 
Companies in this Regiment with the Counties 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.
Company A (Petersburg City Guard) - many men from Petersburg, Virginia
Company B ( Petersburg Old Grays) - many men from Petersburg, Virginia
Company C (Petersburg New Grays) - many men from Petersburg, Virginia
Company D (Lafayette Guards) - many men from Petersburg, Virginia
Company E (Petersburg Riflemen) - many men from Petersburg, Virginia
Company G (Richmond Grays) (formerly Company A of the 1st Virginia
Company H (Norfolk Juniors) - many men from Norfolk, Virginia
Company K (Archer Rifles) many men from Petersburg, Virginia
The information above is from 12th Virginia Infantry, by William D. Henderson
- National Park Service, The Civil War Soldiers and Sailors System, (accessed 6 December 2010).