He hung up the receiver and returned to his survey of the board. "Those three listening-posts," he said abruptly, indicating a place near where an enemy tank had been destroyed. "Have they been reoccupied?" "Yes, sir. Just reported. The tank they reported rolled over them, destroying the placement. They are digging in." "Tell me," said the general, "when they cease to report again. They will." He watched the board again and without lifting his eyes from it, spoke again. "That listening-post in the dead sector, with the two strayed infantrymen in it. Was it reported?" "Not yet, sir." "Tell me immediately it does." The general leaned back in his chair and deliberately relaxed. He lighted a cigar and puffed at it, his hands quite steady. Other officers, scenting the smoke, glanced up enviously. But the general was the only man who might smoke. The enemy's gases, like the American ones, could go through any gas-mask if in sufficient concentration. The tanks were sealed like so many submarines, and opened their interiors to the outer air only after that air had been thoroughly tested and proven safe. Only the general might use up more than a man's allowance for breathing. * * * * * The general gazed about him, letting his mind rest from its intense strain against the greater strain that would come on it in a few minutes. He looked at a tall blond man who was surveying the board intently, moving away, and returning again, his forehead creased in thought. The general smiled quizzically. That man was the officer appointed to I. I. duty--interpretative intelligence--chosen from a thousand officers because the most exhaustive psychological tests had proven that his brain worked as nearly as possible like that of the enemy commander. His task was to take the place of the enemy commander, to reconstruct from the enemy movements reported and the enemy movements known as nearly as possible the enemy plans. "Well, Harlin," said the general, "Where will he strike?" "He's tricky, sir," said Harlin. "That gap in our listening-posts looks, of course, like preparation for a massing of his tanks inside our lines. And it would be logical that he fought off our helicopters to keep them from discovering his tanks massing in that area." The general nodded. "Quite true," he admitted. "Quite true." "But," said Harlin eagerly. "He'd know we could figure that out. And he may have wiped out listening posts to make us think he was planning just so. He may have fought off our helicopters, not to keep them from discovering his tanks in there, but to keep them from discovering that there were no tanks in there!" "My own idea exactly," said the general meditatively. "But again, it looks so much like a feint that it may be a serious blow. I dare not risk assuming it to be a feint only." He turned back to the board. "Have those two strayed infantrymen reported yet?" he asked sharply. "Not yet, sir."