Ted,
Henry Clay Slyoff was born in 1845 near Philadelphia and died 10-23-1864 from scorbutus as a Union prisoner in the famous Andersonville, Georgia camp. He is recorded as Henry Syloff grave number 11365, as a Private in the PA Infantry, Company C, Regiment 81. His parents, James (a Civil War Corporal) and mother Elizabeth Shaffer Slyoff are buried in Northwood Cemetery, Philadelphia, Pa.. He was not married but had brothers Jacob and John, and sisters Margaret, Viola, Mary and Hannah. I do not know any of his personal history as yet.
I also have not been able to find any specifics on Company C or when/how he was capture. If you can help with any additional data it would be greatly appreciated.
Good luck!