The Empty Fort Strategy

A huge army was on the march. Inside the town, almost no one was left. And yet the order from the man defending it was to throw open all four gates, as wide as they would go, with not a single gate left half shut.

It sounds like a terrible mistake. Town gates are made to be closed. When danger comes, people wedge timber behind them, pile up stones, and pack earth against them to hold them firm. Nobody opens them.

Yet that is exactly how the story goes in the Romance of the Three Kingdoms, a classic Chinese novel. People of old told it, and generation after generation of grandparents in Vietnam passed it on. The trick even has its own name. In Vietnamese it is không thành kế, which means the strategy of the empty fort.

The town in the story is Xicheng, a small walled county seat. Its defender was Zhuge Liang, whom people in Vietnam fondly call Khổng Minh. He was a celebrated adviser and strategist of ancient China. He had not come there to fight, but to see to the moving of grain and supplies. He brought 5,000 soldiers, and half of them had already gone ahead with the supply carts. Only 2,500 people remained in the town. There was not one great general at his side, only a group of civil officials, men more used to holding a brush than a spear.

Then the riders came. Not one horse, but more than ten riders galloping in one after another, each bringing the same news. Sima Yi was coming, with an army of 150,000.

When the officials heard it, every face went pale. Zhuge Liang climbed onto the town wall and looked into the distance. Dust rose until it filled the sky. The army had split along two roads, both heading for this one small town.

Then he gave his orders, and this is the moment that makes everyone who hears it stop short.

Take down every banner, and leave not one flying on the wall. Whoever holds a post stays at that post. No one moves about in disorder. No one speaks a single word aloud. Open all four gates wide. At each gate, twenty men are to take off their uniforms, dress as ordinary townspeople, and go out with brooms to sweep the road. When the enemy arrives, keep sweeping. Do not panic, and do not run.

As for himself, he put on his cloak of crane feathers and a silk headscarf. He took two boys with him and a single zither. He went up to the watchtower on the wall, sat leaning against the railing, lit a stick of incense, and began to play.

One boy stood on his left, holding a fine sword in both hands. The other stood on his right, holding a horsetail whisk. Below the wall, more than twenty men bent their heads and swept the road, slowly and steadily, as if no one else were anywhere near.

At that moment the whole town looked more like a stage than a place where something was about to happen. Four gates open. No banners. No drums. Only the scrape of bamboo brooms on the stone, one thin thread of incense smoke rising, and the sound of the zither.

Sima Yi's scouts rode back to report. He burst out laughing and did not believe them. How could a town stand with all four gates open while its commander sat up on the tower playing music? But once he had finished laughing, he still halted his whole army. Then he spurred his horse forward alone and stopped at a distance to look.

And he saw it, just as the scouts had said. Up on the tower sat Zhuge Liang, his face bright and cheerful, as if he were enjoying himself. A stick of incense burned beside him, and his ten fingers moved over the strings. The two boys stood on either side. Down at the gates, the men with brooms kept their heads bent and went on sweeping. Not one of them bothered to look up at the 150,000 soldiers standing right in front of them.

His son, Sima Zhao, rode with him. When he saw his father order a retreat, he would not accept it. Perhaps the man had no soldiers left at all, the son asked, and was only putting on this show. Why was his father in such a hurry to pull back?

Sima Yi answered, and the whole story turns on his answer. All his life that man has been careful in everything he does, and he has never once taken a gamble. Yet today the gates stand wide open. There must be an ambush inside. If our army marches in, we walk straight into his trap.

So the whole army turned around. The rear became the front, the front became the rear, and 150,000 men withdrew along the mountain road to the north.

Not one arrow had been shot. No one was hurt. The four gates stood open, just as they had at the start.

Only when the last of the enemy had passed out of sight did Zhuge Liang clap his hands and laugh.

The civil officials crowded around, eager to understand. Sima Yi was a famous general. He had brought 150,000 picked troops right to the gates, and the moment he set eyes on the chancellor, he turned back. How could that be?

Zhuge Liang's answer was completely honest. That man believes I have been careful all my life, and that I would never take a gamble. Seeing the town like this, he suspected hidden troops, so he withdrew. I was not gambling. I did it because there was no other way left. I have only 2,500 people. If we had abandoned the town and fled, how far could we have run? We would surely have been caught.

The officials were stunned. They admitted, quite honestly, that if the choice had been theirs, they would certainly have abandoned the town and run.

Looking back, what saved the town that day was not the four gates, and not the zither either.

What saved it was the decades Zhuge Liang had spent living carefully. Because he had been careful his whole life, the man on the other side was certain he would not gamble. That very certainty raised a wall in front of the gates that no eye could see. He did not win by inventing some clever way to fool the world. He won because he understood exactly what the man across from him was thinking, and he guessed right.

There is one more thing, perhaps the hardest part of the whole story. For that zither to sound like music, those ten fingers could not tremble. One wrong note would have been enough. One frightened glance toward the dust on the horizon would have been enough. Everything would have been lost. Sitting that still while 150,000 soldiers were advancing may well have been harder than thinking up the trick in the first place.

Afterward, he did not stay to celebrate either. He had the people of that small county town pack up and go with him back to Hanzhong, because he knew for certain that Sima Yi would return.

This story comes from the Romance of the Three Kingdoms, a 14th-century novel traditionally credited to the writer Luo Guanzhong. In other words, it is a story that was told, not a page of history that was recorded. But it was told so well that it traveled very far. In Vietnamese, the three words không thành kế became an expression people often use. When someone has nothing left in hand but still looks steady enough to make the other side hold back, people say that person is using không thành kế.

So whenever those three words come up, that old stage comes back to mind. A small county town, its four gates standing wide open, hiding nothing. A few dozen men with brooms, heads bent, sweeping the road. One thin thread of incense smoke rising straight up. And on the watchtower, a man sitting against the railing, a boy on each side, his ten fingers resting on the strings, playing one more piece until the dust far away has fully settled.