Something interesting about the Colonel...
Have you ever heard of a man named George Armstrong Custer? He was a part of the Calvary during and some time after the American Civil War. After the Civil war he took part in attempting to drive out the American Indians from their homes.
Here is a Picture of him.
See the resemblance?
Custer was eventually killed in the Infamous Battle of Litte Big Horn, a fight between the allied Cheyenne and Lakotas.
Was this resemblance a coendience? I personally think not, seeing how Custer is a recognisable figure in the history of the American west and the part that the man played in attempting to drive out the Native American people would make the Animated Colonel's resemblance to this real person allmost symbolic in my opinion.
Our Animated Colonel is considered the Villain of Spirit's story not becaus he's constantly out to get Spirit (in the Commentary they say all their interactions were completely coencidental), but because of what be believes...
" There are those in Washington who believe the West will never be settled, the Northern Pacific Railroad will never breach Nebraska, a hostile Lakota will never submit to providence. And it is that kind of small-minded thinking that say this horse will never be broken."
The Colonel in Spirit, simply sees Spirit the same way he sees the Native Americans... something that can be eventually broken, tamed, or driven out. Custer probably felt the same way as he and others tried to drive out the Natives; even though I do beleive it was what their superiors had ordered them to do.
In the end for both of these men, both fictional and real; their arrogance became their downfall. At least in the movie, the Colonel understood that Spirit and Little Creek had earned their freedom.