It's not that the Qin army can't besiege the city until next year, but there are too many variables.
Will the Chu army come to the rescue during the siege?
Did King Wei change his mind and go out to fight in the city?
If Chu and Wei unite, then the Qin army may not be able to deal with it.
Therefore, the long night and the long dream should be dealt with quickly.
But what can be done about this situation?
The first and second paragraphs are easier to say. The Qin army organized tens of thousands of people to clear the mud, and it could be completed in three or five days.
But the third section under Daliang City... let alone three or five days, whether it can be completed in three or fifty days is a question.
Shen Bing, who had been silent, made a suggestion:
“Can the first two sections be dredged and the third section built with a dike?”
This is actually easy to understand.
If there is silt blocking the river channel and the water will overflow to the side, use dikes to block it on both sides.
In fact, there is no need to block "both sides", because the other side is Daliang City, that is, you only need to block the side away from Daliang City.
But how could Zheng Guo have thought of such a simple question?
Zheng Guo replied:
"Building a dike may be feasible."
"But the dike still has to be built under Daliang City, and it will take longer. Doesn't this mean the gain outweighs the gain?"
This is what it says.
You must know that the range of crossbows in this era was more than a hundred steps, and the range of trebuchets could even be as high as two hundred steps.
It's true that you don't need to go directly to Daliang City to build a dike, but it's not that far away.
If the dam is built far away, such as a hundred steps away, and there is concern that there will not be enough water to pose a threat to Daliang City...
Therefore, you still have to work under the attack of the Wei army's bows and crossbows when you come and go, which is no better than digging and clearing the river mud.
Shen Bing had a question that he didn't understand, so he asked curiously:
“Why does it take longer to build levees?”
Yang Duanhe and Zheng Guo coincidentally cast strange glances at Shen Bing.
Isn’t it common knowledge that building dams takes longer?
But it turns out that there were two common methods for building dams in this era:
One is to use stones to build along the river bank.
The other is to fill it with wood and rammed earth, and then pound it down.
Otherwise, if the soil is too loose, it will collapse as soon as the river water washes it off.
Neither of these two dam-building methods is fuel-efficient.
Laying stones? This involves the problems of transporting stones and laying them solidly.
Timber and rammed earth? The pounding of logs and rammed earth takes time.
It would be fine if he did it elsewhere, but if he did it within the range of the Wei soldiers' crossbows... it would undoubtedly be life-threatening.
So as Zheng Guo said, doing this is more difficult and troublesome than clearing and digging mud.
Shen Bing asked doubtfully:
"Why don't we use sandbags to build a temporary embankment?"
"Anyway, this dike doesn't need to last long. It only takes a few days for the water to hit the beams and cover it!"
Zheng Tong couldn't help but wonder:
"Sandbag? What is a sandbag?"
Shen Bing secretly thought that there were no sandbags in this era, so he explained:
"Actually, it's just a sack."
“When you fill it with sand, it’s called a sandbag!”
Yang Duanhe was confused after hearing this.
Zheng Guoze said "Oh", widened his eyes and said:
"Is it 'grass wrapped in mud'?"
"The stingy man is saying... use sacks to make 'straw-wrapped mud'?"
"good idea!"
It turns out that it was not that there were no sandbags in ancient times, but that everything in this period was artificial. Even the hemp ropes were twisted one by one, and the sacks were woven by hand.
It is usually used to hold grains. For example, transporting military rations requires many sacks.
It is difficult to make and the output is small, so of course it will not be filled with sand and soil and then thrown to the river... becoming an insignificant piece of temporary dam.
The common method used by the ancients to block water was "grass wrapped in mud" as Zheng Guo said.
It uses reeds, thatch or wheat stalks to wrap clay into a long cylindrical shape, and then tie it tightly with hemp rope to make a sandbag.
The advantage of this kind of sandbag is that it does not require the use of sacks, so it is very cheap. The disadvantage is that the water blocking effect is not good and is affected by seasons and regions.
For example, it is difficult to load stones or sand inside without leaking, and it is still easily washed away by water.
Another example is reed in winter, when there is less thatch, and most of the wheat stalks are burned in the fields. It is not easy to find a large amount of raw materials to make it, and it also requires a lot of manpower and time to make.
Therefore, it was not that Zheng Guo did not think of this method, but that this method was not available and could not be used.
At this time, when Shen Bing heard about sacks, he couldn't help but nodded slowly.
Yang Duanhe asked curiously:
"I heard from Chess that these sandbags can be used to build temporary dams?"
"And it can be done quickly?"
In order to explain it better, Shen Bing simply ordered someone to get dozens of sacks and demonstrate it.
Shen Bing said while directing the craftsmen to work:
"We can fill the sacks with sand first."
"What kind of sand and soil to install depends on the situation."
"For example, sand and gravel that are not easily dispersed in the water can be used near the outer edge of the river."
"The inner edge is made of more stable rammed earth."
"After filling, tie the mouth of the bag tightly, stagger and stack them together where the embankment needs to be built, and the embankment is ready!"
As he said this, he saw craftsmen stacking dozens of sandbags and lining them up, and soon a dam was formed.
After finishing, Shen Bing added another sentence:
"If we add wooden stakes and hemp ropes to tie it up, it will be stronger!"
Yang Duanhe looked at Zheng Guo, as if asking Zheng Guo whether this method was feasible.
Zheng Guo nodded firmly and replied:
"This method works, this method works."
"This sandbag is similar to 'grass wrapped in mud', but I don't know how many times better than 'grass wrapped in mud'!"
“Sacks can tightly gather sand and rocks together without loosening them. Although the water-blocking effect is not as good as that of dams, it is not weak either.”
"Unless the sacks rot and crack due to being soaked in water for a long time, this dam..."
After thinking for a while, Zheng Guo said again:
"Why don't I try it?"
Yang Duanhe asked:
"What kind of trial method?"
In fact, you can really try it.
Zheng Guo found a ditch with a slow flow of water. Ditches like this were everywhere in Wei State.
The reason why it is required that "the water flow is not urgent" is because when the water is blocked and the flow is cut off, the water flow will become more and more rapid, probably to the extent that the water will flood the girders.
Then just do what Shen Bing said:
First, piles were driven into the ditch, and then sandbags were filled in between the wooden piles... As sandbags were filled in one by one, it didn't take long for the water flow in the ditch to be blocked.
Then he continued to fill in some sandbags behind the wooden piles for reinforcement, and a dam stood in front of everyone.
Zheng Guo looked at Shen Bing and sighed:
"This method is very good for blocking water."
"It is fast and effective. Although it consumes many sacks, it is not necessary in emergencies."
This is what is said.
No matter how important the sack is, it can't be more important than destroying Wei, right? No matter how expensive it is, it can't be more expensive than Daliang City, right?
And military emergency time is everything.
Just because you can't use sacks at ordinary times doesn't mean you can't use them at critical moments.
Especially when other methods fail and there is no other way out.
So Yang Duanhe no longer hesitated and immediately ordered: