_Sorry_, Riddell thought. He ripped upward with a crashing right, followed with a left pounded into the guard's stomach. The man staggered backward. Riddell grabbed him by the collar, hit him twice across the face, and he folded. Riddell let the unconscious man sag to the ground. Then he looked around. No one had seen the encounter. The quiet farm-houses remained quiet, the cows in the field ignored the incident, and the cloudless skies did not seem to care. Hastily, Riddell dragged the guard off the road into a thick clump of underbrush and stripped the man's uniform off. It was a tight fit, but he managed to squeeze into it. He tore his own cloak into strips, tied it around the guard's arms and legs, and adjusted his clothing. Then he drew out the guard's wallet and examined it. He was now Corporal Edmund Calder of the Army of Northburg. The new corporal Calder straightened up, cast a backward glance at the unconscious man in the shrubbery, and started walking towards the walls of the city of Northburg. * * * * * There was a gate in the wall about a hundred yards further along the curve. Riddell walked quickly, carrying himself erect in proper military fashion, and reached the gate. He passed through, head down. The man on duty didn't seem to notice that anything was wrong. But as Riddell started to enter the city, the guard said, "Just a minute, Corporal." Riddell whirled, then got control of himself. "Yes?" "I forget to ask you something," the soldier said. He was a private. He was staring full into Riddell's face, and if he knew that the corporal was an impostor he wasn't revealing anything. "The Major wants to know if any prowlers were around while you were on duty." "No," Riddell said uneasily. "No, there wasn't any trouble at all. What's up?" "Trouble from Center City," the guard said. "Seems a couple of kids got through our lines last night and slipped into the city. We caught one, but the other's still around somewhere. Funny you hadn't heard about it." "I've--I've been on leave," Riddell improvised. "Just came back on duty a couple of hours ago, and I guess they didn't fill me in." Without waiting for any further discussion, he turned and moved onward. Northburg looked peaceful enough, he thought. They had rebuilt pretty well, though the telephone lines still seemed to be down, at least in this part of town, and hardly any of the rubble-heaps had been cleared. The townsfolk were going about their business. It might well have been Center City--except for the men in blue uniforms patrolling the streets, and the beaten, harried look on the faces of the people. There was _hope_ on people's faces there in Center City. In Northburg, Riddell saw fear.