Chapter Eighty-Seven: Building a Bridge

Surviving a near-death ordeal was a tremendous boost to morale, both for the small band that had made it through with Liu Ji and for the Tang troops still pouring across the river in endless waves. It showed in their actions: every man strove to be first.

Only a handful who knew the whole story understood how perilous it had truly been.

Liu Ji had come from the staff corps. His greatest strength was not special operations, but planning. In a staff officer’s dictionary, there was no simple divide between success and failure, only different measures for dealing with different outcomes. So from the very beginning, he had never made taking the vine bridge intact his only option.

What if the bridge could not be seized? That was the alternative he and Yu Wensheng had devised: rope descent. Over a distance of some hundred paces, they would artificially create a difference in elevation and use gravity to drop swiftly. During the acclimatization training for snow-mountain and plateau conditions, Liang Zai’s central army had long been drilling in this very method; otherwise, how could it have worked so well?

What the arbalest launched was no ordinary bolt. Its front end was shaped like a five-pronged inverted hook, designed to bite into the ground and hold fast. More than a thousand such bolts had been forged, but the harder part was finding suitable rope. To increase the speed of descent, the rope had been wrapped in leather as well, which created another problem: the landing was dangerously fast. But at such a moment, who still cared?

Hundreds of lifting towers could lower hundreds of men at a time. In only one or two hours, the bulk of the infantry would be across. This fresh force would control both banks of the Badi River and secure the next phase of operations.

After all, horses, supplies, and even senior generals like Feng Changqing could not cross in this fashion. Not every rope was safe; if one snapped midway, not even the immortals could save you.

So Liu Ji had thought of another plan: to span this river with a semi-permanent bridge, using materials that were enough to make one marvel.

Iron cables.

The idea came from a later-age film. The suspension bridge still standing over the Dadu River in Sichuan Province bore a striking resemblance to this place in both terrain and width. Of course, they did not have such deep coffers now, so everything had to be simplified. That was what Liu Ji meant by semi-permanent.

These suspension lines were made from eight thick iron chains, each chain linked from two thousand oval iron rings. Each ring weighed half a jin; each chain thus weighed well over a thousand jin. A chain that heavy could not be hurled even by a traction trebuchet.

The best method, of course, would have been to swim across and then secure the line somehow. But the Badi River beneath their feet was a “weak water,” offering very little buoyancy. For that reason, Yu Wensheng had wracked his brain before coming up with a solution: build a gigantic trebuchet.

Liu Ji knew little about machinery and did not really understand how ancient trebuchets worked. He only knew they operated on the principle of leverage. To fling one end of such a heavy iron chain across, the force required would be equally immense. Thus the trebuchet was soon surrounded by more than a thousand soldiers.

Seeing this great contraption assembled piece by piece, Feng Changqing and the others were as dazed as could be. The main throwing arm, more than ten paces long, had been hewn from the trunk of a single great tree, the remnants of bark still clinging to it. As for the wooden pivots serving as the transmission mechanism, there were as many as fourteen of them. This was nearly the limit of a human-powered trebuchet.

Unlike a counterweight trebuchet, the advantage of this kind was that so long as you had enough manpower, theory said you could generate enough throwing force. It could concentrate the strength of thousands upon a single point and produce immense power.

The drawback, of course, was that it was impractical. So many men, used merely to operate one trebuchet, was a massive waste of human resources. Yet in the right place, it often produced unexpected results, as it did here.

“Commander Liang, my men are ready. Please give the order.”

Yu Wensheng personally climbed up and down, working for quite a while before the giant machine was finally assembled. One iron chain was already hanging from the tip of the throwing arm. To keep the whole thing from falling apart, he added twice as many support timbers before gritting his teeth and going to seek out Liang Zai.

Liang Zai did not agree at once. Instead, he turned to look at Feng Changqing. The latter nodded, and Liang Zai strode forward, waving to his men.

“Brothers, do it the way we practiced. Wait for my command.”

Under his direction, hundreds of men shouted in unison as they slowly pulled on the ropes attached to the wooden pivots. Near the highest point, everyone suddenly heaved together, and the long throwing arm swept through a quarter circle, flinging the chained end high into the air.

All eyes on both banks watched the iron chain flying through the sky. The end that had been hurled with such force rose higher and higher, dragging the rest of the chain after it little by little, like a long serpent in flight, drifting slowly toward the opposite shore.

Liu Ji watched as well, calculating where it would land. As expected, the trebuchet’s force was extraordinary. The chain flew over his head by well more than a dozen paces before coming down with a whistle. Fortunately, it was not moving too fast; the Tang soldiers nearby quickly scattered, and it landed in the mud.

“Bad!”

Liu Ji immediately sensed trouble. After striking the mud, the chain quickly began to draw back toward the opposite bank. This was due to the section laid across the riverbank remaining suspended in the air.

The far end was manageable; Yu Wensheng had anticipated this and ordered it secured to the ground. But on this side, the chain tightened faster and faster. Its weight was so great that even if someone tried to throw himself upon it and hold it down, it would have been useless.

Liu Ji snatched a long spear from a soldier’s hands. Before he could act, a black shadow shot past him, and with a swift thrust the spear jabbed cleanly through one iron ring and pinned it into the mud.

“Hold it!”

Liu Ji shouted. Using the same method, he drove his spear into the gap between two rings and halted the chain’s sliding motion. The soldiers he called over rushed forward, grabbing at it in a flurry, and only when dozens, then hundreds, of men pulled together did they finally draw the chain taut.

The rest was easy. The method of securing it was simple too: several thick wooden posts were driven into the mud by the soldiers with mallets, the end of the iron chain was wound tightly around them, and iron stakes were used to fix it in place. Thus a cable, stretched tight over the river, came into being.

Using the same method, the eight chains were launched across one by one. With six as the base and two as the rails, the rough framework of a suspension bridge took shape. Then the prepared planks were fastened on in turn, and this crude flying bridge, two paces wide and more than a hundred paces long, appeared before everyone as if by magic. The Tang men remained calm enough, but Du Guli and the others were at a complete loss for words.

The Tibetans had spent more than seven months building a vine bridge, while these men had completed theirs in less than two hours from start to finish. What manner of strength was this?

Du Guli was profoundly thankful for his choice: standing with these Tang men who were blessed by the gods.

There was no chance left. Xi Dongzan let out another sigh of despair. Only after the Tang cavalry led their horses across that bridge did he finally give up for good.

He had originally thought the Tang had no means of building a bridge, that their horses and supplies could not cross, and that he, with his cavalry, could wait for an opening. After all, cavalry against infantry, even if a direct clash was not cost-effective, harassment would still be possible. But who could have imagined it?

They had actually built an iron bridge in such a short time!

Iron, no less—the very coarse iron the Tibetans had to pay for with precious horses, and these men had casually used it to build a bridge. That was more dispiriting than a battlefield defeat, because a defeat could be avenged next time. But what could one use to close such a vast gap in national strength?

For the first time, fear took root in Xi Dongzan’s heart. Great Tang, like the towering mountains in the distance, was invincible, impossible to climb. They had expended so much manpower and material resources—was it truly something he could stop on his own?

Compared with such a power, what did it matter to kill one or two warriors?

“Go. Back to Hebu Lao City.”

With a grim face, Xi Dongzan turned his horse around and looked back no more.