Cao Cao dug the Baigou, Pinglu Canal and Quanzhou Canal to transport food during battles. At that time, transporting food through waterways was the fastest and most labor-saving way, so Cao Cao ordered people to dig ditches. Flat canals were used to transport food to the army during battles.

Baigou is a river that was created on the original course of the Yellow River due to irrigation needs after the Yellow River was diverted. Because of the diversion of the Yellow River, Baigou lacks water resources and is often dry. In the eighth year of Jian'an, Cao Cao decided to attack Yecheng, the hometown of his mortal enemy Yuan Shao. He first commanded the troops to capture Liyang in one fell swoop, and then led the army to cross the river from Xuchang. In order to solve the problem of transporting military supplies, Cao Cao ordered the army to dig a white ditch and move Qi The water from the Shuihe River was introduced into Baigou, successfully solving the problem of grain transportation. In the end, Cao Cao defeated Yuan Shao in one fell swoop and pacified the north.

Pinglu Canal and Quanzhou Canal were canals dug by Cao Cao to transport grain when he attacked Wuhuan. The Pinglu Canal rises from the current Hutuo River and flows into the Hushui River. The Quanzhou Canal rises from the Haihe River in the south and reaches Ji Canal in the north. At the end of the Eastern Han Dynasty, the heroes were divided and civil war continued. At this time, Wuhuan, who had originally submitted to the Han Dynasty, took the opportunity to cause chaos and often harassed the border. Later, Yuan Shao's remaining forces fled into Wuhuan territory and colluded with Wuhuan. In the eleventh year of Jian'an, Wuhuan captured Youzhou, and Cao Cao was furious when he heard the news.

The arrogance of Wuhuan made Cao Cao realize that in order to completely eradicate Yuan Shao's remaining forces and consolidate the north, he must conquer Wuhuan. If Wuhuan is not eliminated for one day, the rule outside the Great Wall and Liaodong will never be recovered. Youzhou, Jizhou and other surrounding counties will also be threatened by Wuhuan at all times. Therefore, after careful consideration, Cao Cao decided to use all the strength of the country to expedition to Wuhuan.

To defeat Wuhuan, the supply of food and grass is the key. How to ensure the supply of grain and grass was a difficult problem facing Cao Cao. At that time, Cao Cao's military grain was entirely supplied by eastern Henan and Huaibei. The journey was very long. If he relied on land transportation, he would not be able to arrive in time. Once the army was short of food, the consequences would be unimaginable. What to do? When Cao Cao was bored, Dong Zhao gave Cao Cao an idea: dig two canals, one between the Hutuo River and the Gushui River, and the other between the mouth of the Lu River and the Lu River, and use these two canals to transport military supplies.

When Cao Cao heard this, he was overjoyed and immediately adopted Dong Zhao's suggestion to dig canals. These two canals were Pinglu Canal and Quanzhou Canal. Later, Cao Cao relied on these two canals to transport grain and successfully defeated Wuhuan and unified the north.

Obviously, Baigou, Pinglu Canal and Quanzhou Canal were all opened by Cao Cao for the purpose of transporting grain for the war.