Every good kids movie needs a requisite evil villain, and the Colonel fits the bill in “Spirit.” He is determined to make Spirit fall into line, to the point where he’s perhaps unhealthily obsessed with the heroic horse.
At first, he seems to take only a passing interest in how difficult it is becoming to “break” the wild stallion his men have acquired, but he eventually resorts to starving Spirit for three days just to break the horse’s will. He drinks water in front of a desperately thirsty Spirit to taunt him, makes absurd speeches about how Spirit represents the American West itself, and engages in other such theatrics.
Calm down, dude; it’s just a horse. During the climactic end sequence of the film, the Colonel leads other soldiers on a ridiculously dangerous pursuit of Spirit high up into the mountains, stopping only when the horse makes an Evil Knievel-esque jump across a huge chasm. At this point, the Colonel nods to Spirit, having somehow turned his glassy-eyed hatred into respect.
Other than being a stand-in for the faceless imperialism of the U.S. Military, its not explained what drives the Colonel to be such a hardliner; in another life, perhaps, he could have been friends with Spirit with a friendlier approach, like Little Creek.