We took with us, on this invading expedition, only small‑wheeled trucks, on which to convey the larger projectors, and storage tanks and other heavy apparatus, for the Lone City river ran directly to the point where we planned to conduct our siege.
Some forty large boats were required to carry the men, ammunition and supplies. Mercer and I, with Anina and Miela, traveled as before through the air on the two platforms with the girls. We crossed the Narrow Sea without incident and entered the river.
Several hours up, the river narrowed and entered a rocky gorge, four or five hundred feet wide and a thousand feet deep, with almost perpendicular sides. Along one of these ran the Lone City trail. We passed through this gorge. The river here flowed with a current that amounted almost to rapids. Our boats made slow progress. Finally we emerged into an even wilder country, almost devoid of trees. Here we made our first night's encampment.
Noon of the next day found us approaching the Lone City. We did not need to surmise now that Tao would be warned, for far away on the horizon ahead we saw the beams from his great projectors mounting up into the blackness of the sky. Some four miles from the Lone City the river we were ascending swept off to the right. This was its closest point to the city, and here we disembarked. There were several docks and a few houses, but we found them all deserted.
The Lone City was particularly well suited to defense, even though the lay of the country was such that we were enabled to approach here within four miles, and establish our base in comparative safety. The country was wild and rocky, with few trees. The river bed lay in a cañon. From where we landed, a valley so deep and narrow, it might almost be termed a cañon, also led up to the city.
This valley was some two miles wide, with a level floor, and precipitous, rocky sides towering in many places over a thousand feet. Above it stretched a broken plateau country. The valley had many sharp bends and turns, as though in some distant past it had been the bed of a great river that had eroded its tortuous course through the rock.
The Lone City lay shut in at the bottom of this valley between two of its bends. It was a settlement of perhaps ten thousand people, the only city in the Twilight Country, with one exception, on this hemisphere of Mercury.
We established our field base here at the river, and I devoted the next few days to informing myself of the exact lay of the country, and the methods of defense of the city Tao had provided.
I found this defense the height of simplicity, and for its purpose as effective as it well could be. A vertical barrage of light surrounded the city, extending upward into the air with the most powerful projectors some ten or fifteen miles, and, with those of the spreading rays, forming a solid wall of light at the lower altitudes. There were no projectors past the first turn in the valley toward the river—where they could have been directed horizontally—and none of them on the cliff tops above the city. Thus, although we could not get over this light‑barrage, we could approach it closely in many places.
Tao's tactics became immediately evident. He had thrown an almost impregnable barrier close about him and, trusting to its protection, was making no effort to combat us for the moment with any moves of offense.