He looked not back.

Had he done so, he would have seen the mustangs scattering in every direction over the plain.

But he looked not back.

All that he now cared for was before him; and he plied the spur freshly and galloped on.
He had no need to use the spur.

Black Hawk seemed to think that his credit rested upon the result, and the faithful brute was doing his best.