Their fire was evidently taking effect, for it was this battery which the gunners in the fort were trying to silence—trying blindly, for the German guns were masked by a high hedge and a strip of orchard, and only a tenuous, quickly-vanishing wisp of white smoke marked the discharge. So the Belgian gunners dropped their shells hither and yon, hoping that chance might send one of them home.
They did not find the battery, but they found other marks—a beautiful white villa, on the first slope of the hillside, was torn asunder like a house of cards and a moment later was in flames; a squad of cavalry, riding gayly back from a reconnoissance down the river, was violently scattered; a peasant family, father and mother and three children, hastening along the road to a place of safety, was instantly blotted out.
It was evident now that the Meuse was the barrier which had stopped the army. Far up toward Liège were the ruins of a bridge, and no doubt all the others had been blown up by the Belgians.
Down by the river-bank a large force of engineers were working like mad to throw a pontoon across the swift current. The material had already been brought up—heavy, flat-bottomed boats, carried on wagons drawn by motor-tractors, great beams and planks, boxes of bolts—everything, in a word, needed to build this bridge just here at a point which had no doubt been selected long in advance! The bridge shot out into the river with a speed which seemed to Stewart almost miraculous. Boat after boat was towed into place and anchored firmly; great beams were bolted into position, each of them fitting exactly; and then the heavy planks were laid with the precision and rapidity of a machine. Indeed, Stewart told himself, it was really a machine that he was watching—a machine of flesh and blood, wonderfully trained for just such feats as this.
"Look! look!" cried the girl, and Stewart, following her pointing finger, saw an aëroplane sweeping toward them from the direction of the city. Evidently the defenders of the fort, weary of firing blindly at a battery they could not see, were sending a scout to uncover it.
The aëroplane flew very high at first—so high that the two men in it appeared the merest specks, but almost at once two high-angle guns were banging away at it, though the shells fell far short. Gradually it circled lower and lower, as if quite unconscious of the marksmen in the valley, and as it swept past the hill, Stewart glimpsed the men quite plainly—one with his hands upon the levers, the other, with a pair of glasses to his eyes, eagerly scanning the ground beneath.
And then Stewart, happening to glance toward the horizon, was held enthralled by a new spectacle. High over the hills to the east flew a mammoth shape, straight toward the fort. Its defenders saw their danger instantly, and hastily elevating some of their guns, greeted the Zeppelin with a salvo. But it came straight on with incredible speed, and as it passed above the fort, a terrific explosion shook the mountain to its base. Stewart, staring with bated breath, told himself that that was the end, that not one stone of that great fortress remained upon another; but an instant later, another volley sent after the fleeing airship told that the fort still stood—that the bomb had missed its mark.
The aëroplane scouts, their vision shadowed by the broad wings of their machine, had not seen the Zeppelin until the explosion brought them sharp round toward it. Then, with a sudden upward swoop, they leaped forward in pursuit. But nothing could overtake that monster,—it was speeding too fast, it was already far away, and in a moment disappeared over the hills to the west. So, after a moment's breathless flight, the biplane turned, circled slowly above the fort, and dropped down toward the town behind it.
Five minutes later, a high-powered shell burst squarely in the midst of the German battery, disabling two of the guns. At once the horses were driven up and the remaining guns whirled away to a new emplacement, while a passing motor ambulance was stopped to pick up the wounded.
Stewart, who had been watching all this with something of the feelings of a spectator at some tremendous panorama, was suddenly conscious of a mighty stream of men approaching the river from the head of the valley. A regiment of cavalry rode in front, their long lances giving them an appearance indescribably picturesque; behind them came column after column of infantry, moving like clock-work, their gray uniforms blending so perfectly with the background that it was difficult to tell where the columns began or where they ended. Their passage reminded Stewart of the quiver of heat above a sultry landscape—a vibration of the air scarcely perceptible.