He sat with his chin on his chest, wearily debating the impossibility of meeting a situation in which all humanity might well be involved. His achievement of space travel provided no sense of triumph, and the discovery of the abandoned fortress produced no elation. Not when a desperate emergency requiring a non-existent garrison to report for duty was so probable. Burke sat in the control-chair and could find no encouragement in any of his thoughts.... * * * * * _He heard a trumpet-call and was on his feet, buckling familiar equipment about him. There were other figures all around in this bunkroom, similarly equipping themselves. Some grumbled. There was a rush for the doorway and he found himself one of a line of trotting figures which swung sharply out the door and went swiftly down one of the high-ceilinged corridors. The faces he saw were hardbitten and resentful. They moved, but out of habit, not choice. There were other lines of men in motion. Some rushed in the same direction. Others ran stolidly into branching corridors and were lost to sight. Up a ramp, with the pounding of innumerable feet filling his ears with echoed sound. Suddenly there were fewer men before him. Some had darted through a doorway to the right. More vanished. He was at the head of his line. He turned into the doorway next beyond, and saw a squat and menacing object there. He swung up its side and seated himself. He dropped a helmet over his head and saw empty space with millions of unwinking stars beyond it. He waited. He was not Burke. He was someone else who happened to be the pointer, the aimer, of the weapon he sat astride. This might be a drill, but it could be action._ _A voice spoke inside his helmet. The words were utterly strange, but he understood them. He tested the give of this lever and the response of that. He spoke crisply, militarily, in words that somehow meant this--a word missing--was ready for action at its highest rate of fire._ _Again he waited, his eyes examining the emptiness he saw from within his helmet. A star winked. He snatched at a lever and centered it, snapping sharp, bitten-off words. The voice in his helmet said, "Flam!" He jerked the firing-lever and all space was blotted out for seconds by flaming light. Then the light faded and far, far away among the stars something burned horribly, spouting fire. It blew up._ _Yet again he waited. He doggedly watched the stars, because the Enemy had some way to prevent detection by regular instruments, and only the barest flicker of one among myriad light-specks could reveal the presence of an Enemy craft._