Capt. Blocker
So Captain Blocker was about to retire at the time of the movie.
The movie supposedly happens in 1892 and Benjamin Harrison is said to be the president.
By then there was a mandatory retirement age of 64 for military officers.
Christian Bale was born January 3, 1974. Since Hostiles was released in 2017 it was probably filmed in 2016. So Christian Bale would have been about 43 or 44 when his scenes were filmed, and so about 20 years younger than his character.