Here is some additional information:
He was appointed to West Point from the District of Columbia, entering on July 1, 1867, and was named a Second Lieutenant in the 9th Cavalry on June 2, 1872, was promoted to First Lieutenant on June 28, 1878, and transferred to the 4th Artillery on February 8, 1886.
Historical and Register of the United States Army (Washington, D,C,: Government Printing Office; 1901), vol. 1, p. 355, https://www.google.com/books/edition/Historical_Register_and_Dictionary_of_th/nmpy6_Ya9f8C?hl=en&gbpv=1&dq=thomas+corbin+davenport&pg=PA355&printsec=frontcover
The 9th Infantry Regiment was active in the Dakota during this period.
https://en.wikipedia.org/wiki/9th_Infantry_Regiment_(United_States)