Morgan Addington was the father to Minerva Addington, James W. Pennington's second wife. (See above)
It appears that at the time of the war he was still in Hamilton County Indiana. He first appears in Douglas County in 1900.
I believe that Morgan's parents were John Morgan– b. 13 Oct. 1777 in S.C.; d. 15 Oct. 1857 in Hancock County, Ind.
and Rebecca Thornton – 25 Jan. 1837 in Wayne County, Ind.
If so, Morgan's brother Noah Addington and three of his sons enlisted in the Iowa Infantry in the Civil War. Noah’s son Branson (4th Iowa) was the only one of the four to survive. Noah (29th Iowa) Jefferson Barracks near St. Louis, Mo. Noah’s son Joseph C. (4th Iowa) died in Kentucky and another of Noah’s sons, Sylvester (29th Iowa), died in Arkansas.
Morgan appears in 1850 Hamilton Co Indiana census dwelling 90 with wife Mariah and Louisa J. Adington aged 16.
Spouse Name: Mariah Chew
Marriage Date: 2 Mar 1850
Marriage County: Hamilton
Source Title 1: Hamilton County, Indiana
Source Title 2: Index to Marriage Record 1850 - 1879 Inclusive Vol
Source Title 3: W. P. A. Part One 1850 - 1859 Part Two 1860 - 1869
OS Page: 353
He is again located in Hamilton County Indiana in 1860 census dwelling 1493 with Mariah and children. He remains in Hamilton County in the 1880 census. in 1870 he is in Green Twsp Hancock Co Indiana dwelling 27.
Thus it would appear that Morgan would have liely served with and Indiana Unit during the war. I found no evidence in NPS listing or Indiana rosters for Morgan Addington every serving during the war.