“General,” an aide called to get his attention.

He turned to face the distant village. On each of the two strange siege towers, a soldier waved a red battle flag—the signal that they were ready.

Khenbish nodded to his own flag-bearer. The man stepped forward so he could be clearly seen and waved a silk standard over his head. Out on the towers, the men dropped their banners and concentrated on the odd machines they had brought to the field. They maneuvered the ungainly contraption so that the small bore in the coffin-sized wooden box faced the top of the fortified wall. One of the soldiers pulled a cover off the cannonlike barrel while the others slowly swung the box back and forth. When either of the two devices was aimed directly at an archer or observer on top of the castle wall, it paused for a moment.

Nothing seemed to change. There was no noise, no projectile fired, no indication at all that anything was happening, yet each time one of the barrels focused on a watchman, that man suddenly ducked away and never showed himself again.

The Khan’s emissary looked to Khenbish for some sort of explanation. The taciturn general was studying the parapets through a pane of dark-tinted glass the size of a lady’s hand mirror. He finally turned and noticed the look of confusion on the man’s face. He kneed his horse to edge him closer, and then reached across to hand over the glass viewer.

The diplomat took it by its ornately carved ivory handle and held it up to his eye. He blinked quickly and then peered over the edge to look at the walled city unobstructed. Just as quickly he looked back through the glass.

The shaded glass cast the entire scene in an eerie twilight despite the bright sun, but that wasn’t what had startled him. It was the solid rays of light, as thin as rapiers’ blades, that emanated from the two towers. The crimson beams shot like lances from the odd structures and raked across the top of the walls. As he watched, a guard popped his head into the gap between two crenellations. Both beams zeroed in on him instantly. The light raked across his face, and though the distance was too far to be certain, the emissary thought the beams centered in the guard’s eyes. It took only seconds for the hapless man to duck down again, his head shaking furiously.

He lowered the glass a second time. The sepia tint was gone; the ruby rays of light too. Everything was still and placid except for the movement of the two wooden boxes being turned back and forth, their purpose, without the glass, unknowable.

His expression was even more uncomprehending than just moments before.

“Dragon’s Stare,” Khenbish said without turning. “That is what my men call it.”

“And you,” the envoy asked, “what do you call it?”

Khenbish tugged at the reins to wheel his horse around. “Certain victory.”

“I don’t understand. How does it work?”

“There is a long octagonal crystal in each device from an ancient mine far to the south. Do not ask me the science, but using a set of mirrors with holes in them, it somehow channels sunlight captured in the cone on top and focuses it in such a manner that it can temporarily blind a man who gazes directly into it.”

“Yet it is somehow invisible?”

“It appears as a small red dot when it strikes an object, but the beam can only be seen in the air through that glass you are holding.” He turned his focus back on his horsemen. “Now is the time to end this siege.”

The Khan’s man once again regarded the towering ramparts and the thick wooden gate. It seemed as impenetrable as the Great Wall to the north of the capital. He couldn’t understand how blinding a few lookouts could possibly end a siege. But then he came from a family of merchants and knew nothing of warfare or military tactics.

“Charge,” Khenbish ordered.

Though the emissary expected a wild explosion of man and beast racing for the distant walls, the attack was instead a stealthy and slow walk. The horses’ hooves were muffled with thick woolen sacks so they barely made a sound as they moved. Harnesses, saddles, and panniers had all been cinched so tightly that the usual creak of leather was absent, and the men urged their mounts with soft whispers. Closing his eyes, the emissary couldn’t tell that fifty horsemen were trotting past. Of all his senses, only his nose detected the faint whiff of dust kicked up by the animals’ muffled hooves.

Though not a military man, he knew instinctively that this was the critical phase in the general’s plan. He glanced up. The sky remained clear directly overhead, but a single puffy cloud was moving toward the battlefield. Its shadow cut like an eclipse across the hills behind the town. If it swept over them, he feared Khenbish’s secret weapon would be rendered useless.

No lookout had shown himself for many minutes. He could imagine the anxiety and confusion among the defenders, not knowing what had struck them or how it had rendered them blind. This wasn’t a particularly large community, and he knew from his travels that rural people tended to be superstitious. To what manner of witchcraft had they ascribed their sightlessness?

Like an army of ghost soldiers, the column of horsemen was making deceptively good time across the fields. The mounts were so well trained that none whinnied or neighed.

The cloud was still several minutes away. The emissary did some quick calculating in his head. It would be a near thing, and yet the riders didn’t quicken their pace. The general instilled discipline above all else.

A head popped over the wall, and both light cannons swung on him so quickly that he got the barest glimpse of the battlefield before his retinas were seared by the invisible beams. Khenbish stiffened on his horse, waiting for a cry of alarm that would signal unseen archers to release their arrows. A scream from above caused him to suck air through his teeth. It was nothing more than a crow in the branches of a tree behind them.

The lead rider reached the wooden gate and casually tossed the bag he’d been carrying in the dirt at its foot. A moment later another joined it, and another. And another. The pile grew until it was a misshapen hillock pressed up against the stockade.

Finally someone within the walls showed some intelligence. When he raised his head over the battlements just to the right of the gate, he kept one hand shaded over his eyes and his gaze downward. His warning shout carried clearly across the field. The element of surprise had been shattered.

The riders abandoned their pretense at stealth and quickly had their horses at full gallop. The last few hurled their bags at the gate and wheeled around. They scattered as arrows fired blindly from within the walls once again darkened the skies.

But it wasn’t so much the arrows blotting out the sun as it was the cloud that had been so silently approaching. And by some twist of fate the winds that had sustained it ceased, and it hovered like an enormous parasol over the village. Without direct sunlight, Khenbish’s ray guns were nullified.

Alert sentries realized what was coming and started throwing buckets of water onto the pile of bags that reached almost halfway up the thick wooden gate. The general had anticipated this and made certain each had been coated with a thick layer of resin so the water couldn’t permeate it.

Motivated by desperation, archers appeared along the wall and took careful aim before loosing their arrows. The horsemen wore armor on their chests, and helmets covered their heads, but their backs were exposed, and soon arrows found their marks. In moments there were several jockey-less horses milling on the field, their riders lying sprawled on the ground, some writhing in agony, others ominously still.

One of Khenbish’s men raced parallel to the wall, standing high in his stirrups, a nocked arrow ready in his short cavalry bow. Rather than a sharp bronze point, the arrow’s tip was a pitch-soaked wad of cloth that burned brightly. He fired and immediately pulled hard on the left rein. The horse knew the signal and went down onto its flank in a cloud of dust, its legs kicking awkwardly while its heavy body shielded the rider from what was to come.