In the Zhou Dynasty, the capital city was frequently attacked by tribes nearby. To facilitate the reinforcement of vassal states, beacon towers were set up within a certain distance of one another on all roads to the capital for warning of danger.

According to the rule, once troops were needed for rescue, the beacon tower nearby would send out thick smoke during the day and big fire during the night. Adjacent towers would follow suit.

At the same time, the beacon tower should beat the drum and other towers were supposed to do the same after hearing the drumbeats. Thus, all vassal states around would immediately send out troops to rescue.

One day, in order to please his favorite concubine Bao Si, King You of Zhou ordered his men to ignite fire at the beacon tower and he himself even beat the drum. Then, vassals nearby all rushed to the scene, only to find there was no danger at all. They were outraged after learning about the truth. Seeing that everyone was fooled, Bao Si felt happy.

After that, King You of Zhou repeated his false alarm for several times just to make Bao Si happy. But there were fewer and fewer vassals coming to help. At last, when enemies did come, no vassals sent any troops. King You of Zhou was killed and his state came to an end.