The answer is in the next two sentences of the Texas Historical Commission marker:

“Realizing his tactical disadvantage, Mackenzie ordered the Indian camp and supplies burned and withdrew, taking along 1,400 captured horses (1,000 of which he later destroyed).

Having lost half their horses as well as all their supplies and shelter, the Indians drifted back to their reservations at Fort Sill and Fort Reno.”

The battle was not a killing event.

It was a destruction event.