The colors ranged from piebald to grey and there was a great diversity in stature.

Presently the black stallion neighed softly, whereat the rest of the herd bunched closely together, the mares with the foals on the side, and all heads turning towards the black who now galloped to a hilltop, surveyed the horizon and presently dropped his head to graze again.
This was a signal to the others.

They spread out again carelessly, but Alcatraz was beginning to put two and two together in his thoughts.

The two stallions were obviously guards, but what should they be guarding against in the broad light of day except that terrible destroyer who hunts as well at noon as at midnight--man! Inspiration came to Alcatraz.
The difference of color and stature, the unkempt manes and tails, the wild eyes, were all telling a single story, now.

These were not servants to man, and since they were not his servants they must be enemies, for that was the law of the world.