Marion Rowland is the older brother to the above Samuel Rowland see 1850 and 1860 census list.

1870 has him here
Name: Marian Rowland
Age in 1870: 30
Birth Year: abt 1840
Birthplace: Missouri
Home in 1870: Township 51, Boone, Missouri
Race: White
Gender: Male
Post Office: Sturgeon
Occupation: Stock Drover
Cannot Read: Y
Cannot Write: Y
Male Citizen over 21: Y
Personal Estate Value: 3000
Household Members:
Name Age
Marian Rowland 30

Married 1866
Name: Marion M Rowland
Marriage Date: 6 May 1866
Marriage Place: Boone, Missouri, USA
Spouse: Davidella Wingo

I found a reference to a Marion Rowland on a pension index card filed by his wife listing service as a Pvt Co C 4th PEMM and Co B 51st EMM This matches https://www.sos.mo.gov/Images/Archives/Military/s00892/s00892_2178.pdf
This may be a different Marion as it appears this guy enrolled at Richmond, Ray County in 1864.

There is then this reference card in MO SOS
https://www.sos.mo.gov/Images/Archives/Military/s00738/s00738_0752.pdf
This references "with Porter" by Mudd