The twilight beyond faded into the darkness of the huge forest, and not a Perlac was to be seen. Not so much as a moving shadow. But they were there, Mark knew, thousands of them; and when they came it would be silently. And silently they came. Mark's first intimation was the explosion of grenades far down the line, and then he saw them--hordes of Perlacs, heavy of limb, but coming with amazing speed. Most of them were using cross-bows, and Mark realized that some of the shafts were equipped with metal-tipped explosives. Then he was too busy for further observation, as he brought his atomic rifle to bear. The old style electrics were at work too, all along the line; and the grenades blasted huge gaps in the advancing tide. But still they came, moving now across the lighter zone. Thousands hadn't been an overstatement! The dark tide came rushing over their stunned and dead. And now those explosive tipped shafts were having effect. Several of them struck a barricade next to Mark, and tore the metal from the foundations. Now Janus, beside him, was bringing the neutro-pistol into play. Savagely Mark swung his beam in a never-ceasing arc, exulting at the swath it cut before him. Further down, Driscoll, Kaarj and the others were doing the same. Together with the grenades it seemed to stem the tide, but only for a moment. "Keep it going! Keep it going!" Janus was yelling. "These beams are good for hours!" The very silence of the attack made it the more terrible. No yells, no screams of fury came from the heavy-furred Perlacs as they littered the terrain by the score. Then, as suddenly as they had come, they retreated. The seven sweeping beams had done the work well, but in an unexpected manner. Flames were leaping in the lush grass between the defenders and the forest! "Respite!" Janus yelled. "Ten minutes, maybe. They'll be back when that grass is burned down!" But there was no resting now. A score of men were dead and twice that many wounded, who had to be carried back from the battle line. Three of the barricades were wrecked, and they strove to get these into place again. Mark noticed Mari, sweat-grimed and weary, her golden hair streaming down. But she was magnificent still, a tower of strength as she hurried along the line giving aid and encouragement to her people. "I wonder where the robots are?" Mark suddenly remembered as he worked beside Janus. "If the Perlacs have learned to reactivate those monsters, as Donli thinks--" "Encouraging, ain't you? As if we're not having a hard enough time as it is!" And then Mark remembered something else. Remembered so suddenly that he began laughing, a little wildly, and Janus slipped him a light one on the jaw. "Come out of it, lad! None of that, now--we're not licked yet!"