Patrol

MacMartree knew that Man was omnipotent—Master of the Universe. But could he expect his patrol to fight and conquer an invisible enemy?
They made their camp high on the breast of the gently swelling hill. As the small planet turned toward the sunset, MacMartree stood a moment on the hillside, watching. Far out on the grass-covered plain their ship stood gleaming, a slender candle, touched by the flame of the sinking sun. Then, quickly, the far horizon caught the sun and pulled it under, and the gloom of night rushed in to drown the pale twilight.
Night comes so fast here, Abner said, at MacMartree's side.
Yes, MacMartree agreed, turning to him. And day comes even faster. Time for sleep now, with morning only four hours away.
I can't get used to it, Abner said as they moved back into the camp area. Sleeping and waking in four hour bits!
MacMartree laughed at that. Abner, you're getting old. You can't adapt anymore.
Abner laughed, too, and unrolled his sleep-kit for the night.
MacMartree walked to the place where Phillips and Cole lay on the ground, talking casually and watching the stars.
Time to switch on the screen, Phillips, MacMartree reminded the younger man.
Phillips nodded, sat up and reached for the control box that lay on the earth beside him. He closed the circuit, and the force-screen bloomed around them, glimmering softly like a thin veil of glowing fireflies.
Kind of useless, that, don't you think? Cole asked.
MacMartree sat down beside them.