The ancient "Eight-Unit Formation", also called Eight Element Battle Formation, was a battle array formed by eight fighting units which were represented by Heaven, Earth, Wind, Cloud, Dragon, Tiger, Bird and Snake. Of the kaleidoscopic scenes near Fengjie and Baidi City (White Emperor City), the most distinctive is the former site of the Eight-Unit Battle Formation designed by Zhuge Liang. The "Biography of Zhuge Liang" in the Annals of the Three Kingdoms says that "Zhuge Liang drilled his soldiers and invented the Eight-Unit Battle Formation". Over the centuries, stories about Zhuge Liang's almost superhuman stratagems have shrouded the Eight-Unit Formation in mystery.

It was said that Zhuge Liang set up four Eight-Unit Formations: One in Mian County, Shaanxi Province; another in Xindu County in Sichuan Province. The third one is an Eight-Unit Water Formation by the Yangtze River to the east of the town of Fengjie and the fourth one is an Eight-Unit Dryland Formation neat the Thatched Cottage in the northeast of Baidi City. The last one is therefore also known as the Eight-Unit Formation of the Thatched Cottage. The most famous one, however, is the water formation in Fengjie. Is was said that Zhuge Liang took the topographical advantage and set his Eight-Unit Battle Formation here on the beach, which almost bottled up Lu Xun, a general of Wu Kingdom, and thousands of his soldiers.

The Eight-Unit Water Formation is located at the mouth of Meixi River, which flows into the Yangtze. It is a vast expanse of sandy beach with stones of different sizes scattered all over. The scene changes with the rising and falling of the river. The formation was built by stones and sand deposited by flood waters of the Yangtze and Meixi rivers on a shoal, which is exposed during the low water season. There is a salt spring on the shoal, and when the shoal is exposed, people come in crowds to make salt by boiling the water from the salt spring. Stoves are built here and there stretching for several thousand meters and presenting a spectacular scene at night. The place is therefore also known as Salt Shoal. It was said that to defend Shu against the invasion by the kingdom of Wu, Zhuge Liang came to Fengjie twice. It was quite possible that he came to make the necessary arrangements and built the battle formation on the broad shoal.

The Eight-Unit Water Formation
According to the Annals of Military Preparations by Mao Yuanyi of the Ming Dynasty, Zhuge Liang's Eight-Unit Formation was a battle array composed of sixty-four small units arranged in lines and files which form a large battle formation. There were twenty-four mobile troops of cavalry in the rear of the formation to coordinate in the fighting. The sides of the formation are several kilometers long. The mountain town of Fengjie looks a very likely place for drilling soldiers for battle.

Many essays and poems have been written since ancient times about the Eight-Unit Formation. The best known is a poem by Du Fu, which reads:
He achieved more than anyone of the Three Kingdoms,
And earned his fame with the Eight-Unit Formation.
The river flows on, but the stones are immobile.
Failing to conquer Wu caused his bitter remorse.
Zhuge Liang set himself the task of destroying Cao Cao and conquering the kingdom of Wu, But his plans were defeated by the hasty moves taken by Liu Bei to avenge his sworn brothers. This surely moved Du Fu to write the above poem.

In historical times, it was a tradition for people of Fengjie to come out on the seventh day of the first lunar month to make excursions to the Salt Shoal. Women picked up pebbles and used them as ornaments on the head, which they believer would bring them good luck. This tradition lasted until the Ming Dynasty before it was discontinued.