Stewart pulled his hat forward over his eyes as though to shield them from the light. Then he went carefully back over the sequence of events which had led them to this compartment. It was Hans who had brought them to it--and Hans was a spy. It was he who had selected it, who had stood at the door so that they would go no farther. It was he who had slammed the door. Was the door locked? Stewart's hand itched to try the handle; but he did not dare. Someone was perhaps watching as well as listening. But that they should be permitted to enter a carriage reserved for officers--that, on a train so crowded, they should be undisturbed in the possession of a whole compartment--yes, it was proof enough! The station-master's whistle echoed shrilly along the platform, and the train glided slowly away. Darkness had come, and as the train threaded the silent environs of the town, Stewart wondered why the streets seemed so gloomy. Looking again, he understood. Only a few of the street lights were burning. Already the economies of war had begun. The train entered a long tunnel, at whose entrance a file of soldiers with fixed bayonets stood on guard. At regular intervals, the light from the windows flashed upon an armed patrol. Farther on, a deep valley was spanned by a great viaduct, and here again there was a heavy guard. The valley widened, and suddenly as they swept around a curve, Stewart saw a broad plain covered with flaring lights. They were the lights of field-kitchens; and, looking at them, Stewart realized that a mighty army lay encamped here, ready to be hurled against the French frontier. And then he remembered that this was not the French frontier, but the frontier of Belgium. Could the landlady of the Kölner Hof have been mistaken? To make sure, he got out his Baedeker and looked at the map. No; the French frontier lay away to the south. There was no way to reach it from this point save across Belgium. It was at Belgium, then, that the first blow was aimed--Belgium whose neutrality and independence had been guaranteed by all the Powers of Europe! He put the book away and sat gazing thoughtfully out into the night. As far as the eye could reach gleamed the fires of the mighty bivouac. The army itself was invisible in the darkness, for the men had not thought it worth while to put up their shelter tents on so fine a night; but along the track, from time to time, passed a shadowy patrol; once, as the train rolled above a road, Stewart saw that it was packed with transport wagons. Then, suddenly, the train groaned to a stop. "The frontier!" said Stewart to himself, and glanced at his companion, but she, to all appearance, was sleeping peacefully. "We shall be delayed here," he thought, "for the troops to detrain," and he lowered the window and put out his head to watch them do it.