Zhang Yi quickly wrote the reply, and he was worried that Xue Li and they would not be able to conceive of what the rocket should do, so he attached a construction diagram by the way.

On the picture, Zhang Yi marked Xue Li in great detail how to operate them.

In order to reply to Xue Li as soon as possible and give him more time to make the rocket, Zhang Yi drew the structural diagram overnight and wrote the letter.

At dawn the next day, Zhang Yi did not fry the letters, but immediately sent the letters to the front line.

He doesn't have the power of Xue Li to send letters expeditiously, and Xue Li can go through official channels, because he is now a pioneer officer, and he has this power.

And Zhang Yi is now just an ordinary nobleman who is idle at home, and he is not qualified to enjoy the treatment of eight hundred miles of expedited.

He was only able to send letters through the normal channels.

And ordinary channels, such a long distance, by the time his letter is sent to the front line, it is estimated that it will be seven or eight days later, and this is fast enough, if it encounters rainy weather, or because of other natural reasons obstruction, then his letter may not be able to reach the front line.

But there was no way, Xue Li used the method of urgent encryption, he just didn't want others to know, and he naturally couldn't let others know, otherwise Xue Li's actions would not be in vain.

Moreover, the rocket structure diagram in the letter is very important, and once it falls into the hands of others, it will be very dangerous, so Zhang Yi does not plan to take any special channels.

On the contrary, these ordinary channels are the safest, although a little slower, but for Tang Jun, who has three months, he can still afford to wait.

After the letter was sent, Zhang Yi didn't take this matter to heart, after Xue Li received his letter, he would definitely capture the capital of the Goguryeo people, which was confident that Zhang Yi still had.

Then, next, Zhang Yi can continue to be busy with his affairs, it has been a month since the creation of people, and the stomachs of several of them have not changed a little, Zhang Yi feels that he should speed up his pace a little.

The family is full of children and grandchildren, and they don't have to worry about not being able to afford it.

Not to mention other industries, just this cattle farm run by Bu Fat is enough for them to live a rich and noble life for several lifetimes.

Zhang Yi didn't talk about it for the time being, the letter he sent arrived at the Tang army camp ten days later, and directly arrived in Xue Li's hands.

To be honest, when he received Zhang Yi's reply, Xue Li was excited.

Zhang Yi is willing to reply to him, even if the letter is scolding him, then he will feel better, besides, he is willing to reply to himself, which shows that their relationship has not been broken.

Xue Li couldn't wait to open the envelope and see what Zhang Yi was going to say to himself.

At the beginning of the letter, Zhang Yi still responded to Xue Li's previous explanation, saying that he didn't care about those things, and the friendship between them would not change because of those things.

When Xue Li finished reading this paragraph, his hanging heart was put down, fortunately Zhang Yi was generous, otherwise as long as he publicized it a little, then his reputation would immediately stink.

At that time, he will become a person who doesn't even care about his noble Bole, who is willing to help himself at that time, an ungrateful person, no one will be with him.

After reading Zhang Yi's previous paragraph, Xue Li continued to look at the later paragraph, and Zhang Yi's later words made Xue Li's mouth grow in shock.

"He is worthy of being the most accomplished master in thermal weapons, I have a question, and he will be able to create a new type of thermal weapon immediately, it seems that the last time he created a powder bullet, it was not luck."

"He's got the real ability."

Xue Li thought so, and he respected Zhang Yi even more in his heart.

Such a person can be called a genius, and he is so generous and easy to get along with, it's simple.

Looking at Zhang Yi's reply, Xue Li was more and more happy, and when he saw the construction diagram of the rocket that Zhang Yi attached at the end, Xue Li kissed the letter directly.

"It's so good at thinking, careful, and directly helped us solve the biggest problem at present."

Xue Li was very excited in his heart, with these rockets, countless Tang Army soldiers could go home alive.

Although Zhang Yi did not participate in this war, Xue Li felt that Zhang Yi's credit was no less than that of those generals who led troops to fight, and even his credit was not below him.

And in the long run, Zhang Yi's creations are of epoch-making significance for the Tang Dynasty army and even for the entire Tang Dynasty.

If rockets and gunpowder shells can be popularized to every army of Datang, so that they can learn and skillfully use these weapons, then Datang's army will enter the era of hot weapons.

In this era, the emergence of hot weapons can be said to be a completely new era, and there are too many advantages of hot weapons over cold weapons.

Let's just say that if the Datang army enters the era of hot weapons, then they are fully capable of dominating the world.

The excited Xue Li couldn't stop at all, so he directly sent someone to prepare some bows and arrows for him to experiment.

He had to immediately make the rocket that Zhang Yi said, and only by making some samples would they be able to manufacture and produce them on a large scale.

And when they are done, they have to familiarize the soldiers with these rockets, teach them and teach them, so that they can use these rockets as skillfully as they use bows and arrows.

By the time the Tang soldiers skillfully used rockets, it would be when the capital of the Goguryeo people was shattered!

Xue Li confidently began to make gunpowder, and under the advice of Zhang Yi in his letter, when he made the first rocket, he burned the construction diagram given by Zhang Yi.

In fact, Xue Li had already imprinted that picture firmly in his heart, and even if he burned it, he could clearly remember what the structure of each place was.

The reason why he burned it every time he read it before was because he was afraid that he would miss it, and when the rocket couldn't be made, he also burned the drawings, and then he would become a sinner.

But now it was different, the first rocket had been made and could be used, and he had memorized every corner of that drawing, and he would not forget it at all, and he could even copy it at any time according to the drawings in his mind.

It's just that he won't, it's not an exaggeration to say that such drawings belong to the top secret, any country, no, even any force, as long as they get such drawings, then their combat effectiveness will increase by leaps and bounds, these are not good things for the Tang Army.

Especially if such drawings fall into the hands of hostile forces, it will be a disaster for the Don Army.

Xue Li didn't want to be that sinner, so he chose the safest way.

As the first batch of finished rockets was made, Xue Li immediately found a group of archers and began to test them.

It took a few days to see if the rocket that Zhang Yi proposed could have any effect?

Success or failure depends on the next experiments of the archers.

If it succeeds, then the victory of the Tang army can basically be determined, and once it fails, then everything will be confusing again......