Dennis, I'm afraid that I'm no great shakes when it comes to purely genealogical research. One hint that might help--the other Looper men who were recruited in the same area as Marcus A. Looper were all born in South Carolina. You might want to check the 1850 census of South Carolina and see if you find him there. He would be about 7 years old on the 1850 census.

Also, he was apparently a twin. A man named Henry M. Looper, who served in the 2nd Arkansas Infantry, U.S. Volunteers, was born in South Carolina on July 13, 1847 -- the same birthdate as Marcus A. Looper, though I don't have a record of Marcus' birthplace. This man died on January 9, 1887; Marcus died on January 16, 1922. Both men enlisted at Waldron, Scott County, Arkansas -- Marcus in the Confederate army, Henry in the Union army. This cannot be a mere a concidence. So, when you check the census, look for a Marcus and Henry Looper with the same age living in the same household.

You might also want to post a query on the Scott County, Arkansas, USGenWeb site, and maybe a real genealogist can give you far better help than I can.