They knew that the Comanches were horse Indians--a significant fact.

These centaurs of the central plateaux, scarce ever setting foot upon the earth, when afoot are almost as helpless as birds with their wings plucked or pinioned.
If they could reach the crest of the cliff, then all might yet be well; and, cheered by this reflection, they rushed up the rock-strewn ravine, now gliding along ledges, now squeezing their bodies between great boulders, or springing from one to the other--in the audacity of their bounds rivalling a brace of bighorns.
They had got more than half-way up, when cries came pealing up the glen behind them.

Still were they hidden from the eyes of the pursuers.
Jutting points of rock and huge masses that lay loose in the bed of the ravine had hitherto concealed them.

But for these, bullets and arrows would have already whistled about their ears, and perhaps put an end to their flight.

The savages were near enough to send either gun-shot or shaft, and their voices, borne upward on the air, sounded as clear as if they were close at hand.
The fugitives, as already said, had reached more than halfway up the slope, and were beginning to congratulate themselves on the prospect of escape.