Sertorius (17.5-17.6)

On that day, then, the soldiers of Sertorius worked until night, and were then led back to camp. But when the next day came, at first a gentle breeze arose, stirring up the lightest portions of the gathered soil and scattering them like chaff; then, when Caecias was blowing strong with the mounting of the sun and covering the hills with dust, the soldiers came and stirred up the mound of earth to the bottom and broke up the lumps, while some actually drove their horses back and forth through it, throwing up the loosened earth and giving it to the wind to carry.

Then the wind caught up all the earth thus broken and stirred and threw it up against the dwellings of the Barbarians, which opened so as to admit Caecias. And the Barbarians, since their caves had no other inlet for air than that against which the wind was dashing, were quickly blinded, and quickly choked, too, as they tried to inhale an air that was harsh and mingled with great quantities of dust.