At this time, the Tang army began to charge, a large number of Tang officers and soldiers with shields, rushed to the city, they did not set up a ladder to climb the city wall, but towards the city wall where there was no fire, threw small clay pots, the entire city wall burned without leaving a gap.

Then, the bed crossbow also began to be fired, and the tall city gate was quickly engulfed in flames, and it was quickly burned down.

The Goguryeo people were dumbfounded, they didn't know what kind of weapon the Tang army used, and it was so powerful.

It turned out that the Don Army used gasoline.

China was one of the first countries to discover and exploit oil. As early as the 1st century A.D., there was a record in the Eastern Han Dynasty Bangu's "Hanshu Geographical Chronicles" that "Gao Nu has water that can be burned". During the period of Emperor Shenzong of the Northern Song Dynasty (1068~1085), there were "fierce fire oil tanks" for processing crude oil and "fierce fire oil tanks" for processing crude oil. It can be seen that oil was already used in the military at this time.

Yanzhou (Yan'an) is rich in black oil (oil), the oil layer is very shallow, and in many areas, black oil can be seen on the surface.

As early as 637, the institute established an oil refinery in Yanchang County, which successfully refined kerosene and gasoline and applied it to the military. This is the first time it has been used in real combat.

The fierce fire not only burned the offensive of the Goguryeo people, but also destroyed their psychological defenses. With the collapse of the city gate, the Goguryeo army had no intention of fighting and opened the east gate to escape.

Xue Rengui adopted the tactic of encircling three queyi, deliberately leaving a gap in the east, letting the Goguryeo people out of the city, and after the Goguryeo people left the city, he sent cavalry to seize the east gate and cut off the Goguryeo people's retreat.

The Goguryeo army desperately fled eastward, and was happily annihilated by the two cavalry divisions of the Tang Army, which had already been ambushed.

The entire siege battle took only 5 and a half hours, and at the cost of 2,400 casualties, 21,000 Goguryeo troops were annihilated and Liaocheng was recovered.

Li Shimin came to the burned city gate and sighed very much at the power of the gasoline bomb. In the past, it was basically difficult to succeed in attacking such a fortified city without a few months and tens of thousands of soldiers without dying!

Xue Rengui once performed well in aiding Tuyuhun and conquering Linyi State, and he had already registered in Li Shimin's heart, and today's siege campaign made Li Shimin appreciate it very much.

In the following time, the Tang army relied on advanced equipment such as gasoline bombs to capture most of the cities in Liaodong in succession.

The prime minister of Goguryeo, Izumi Gai Suwen, was very depressed, and he found that the tactics that had worked well against the Sui Dynasty and the Tang army in the early Tang Dynasty were now not working at all. In order to preserve his strength, he took the initiative to give up part of the city and retreat the Goguryeo army to the area east of the Yalu River.

By the eve of the Spring Festival in 642, the Tang army succeeded in recovering Liaodong and advancing the battle line to the Yalu River.

On this day, Mo Kruli, commander of the Buyeo Army, went to the headquarters of the Tang Army in Kuandian to meet Li Shimin.

Mo Kruli was extremely envious of the Tang Army's equipment, and he came to ask Li Shimin for help.

Speaking of the equipment of the Tang Army, Li Shimin was also proud.

So far, the equipment of the Tang Army is the most luxurious in the world.

One cavalry of the Tang army, equipped with a horse, saddle, stirrups, vest. A Mo knife, a horizontal knife, a dagger, a bow, a hand crossbow, each with 30 arrows. A kraft water bag, a dry food bag, two masks, two first aid kits. Big-toed shoes, leather gloves, fur coats, leather hats, quilts (after the capture of Gaochang Kingdom, cotton has been widely used in the Tang Dynasty.) )

A cavalry squad is equipped with two rubber wagons, a tent, a kerosene stove, three sapper shovels, a copper kettle, 12 sets of cutlery, three sapper shovels, three wooden shields, and various scattered utensils.

The cavalry company was equipped with a cooking squad, a baggage squad, and the commander was equipped with a telescope and a compass.

The regimental level is equipped with an engineer company, a baggage company, and a health team.

The division is equipped with a fire team, a baggage battalion, and a field hospital.

The officers and men were well fed, and there were good salaries, bonuses, and pensions.

Compared with the Tang Army, the Buyeo Army is like a flower child. The equipment of only one cavalry division of the Tang Army, in terms of value, exceeded 25 times that of the Buyeo army and 20 times that of the Goguryeo army.

The army of Emperor Yang of Sui back then and the current Tang army are even more incomparable. Emperor Yang of the Sui Dynasty's army could not keep up with the logistics back then, and most of the people died of cold, starvation and disease. A very small number of the Don Army were attrition because of non-combat attrition.

In response to the plea of Mo Cruli, the commander of the Buyeo Army, Li Shimin gave them a large amount of food and some ordnance with a stroke of his pen.

On the eve of the Spring Festival, Fang Xuanling asked to see him.

When Li Shimin saw Fang Xuanling, he asked happily, "Xuanling, why are you here?" ”

Fang Xuanling said: "Your Majesty, the old minister misses you, so he came to see you." ”

After the two exchanged a few words, Fang Xuanling said: "Your Majesty, the minister came this time and brought 200,000 troops and supplies. ”

Li Shimin was unhappy and said, "Do you need so many people to fight a Goguryeo?" Isn't this a waste of money and labor? ”

Fang Xuanling said: "Your Majesty, don't be angry first, please listen to the minister's explanation." ”

Two months ago, Chang'an City, East Palace.

Fang Xuanling was in charge of the logistics support of the Tang Army's Eastern Expeditionary Force, and he was reporting the situation to His Royal Highness the Crown Prince, he said:

"Your Highness, the minister has set up 3 transfer stations in Hebei Province, and the supply of materials ensures that they can reach the front line in time.

According to your request, each prefecture of Guannei Province, Hedong Province, Henan Province and Huainan Province dispatched a reserve regiment, a total of 91 regiments and 200,000 people, each to transport a division of food and supplies for three months, to the front line in Liaodong, and to replenish the Eastern Expeditionary Army on the spot.

Your Highness, your supplementary plan has very little pressure on the states, with an average of only 100 people per county, and not only have no opinions at the local level, but they are all selecting the best reservists, and they are very motivated. ”

Li Su said: "Very good. Lord Fang, please work hard and go to Liaodong to meet the emperor in person. ”

Fang Xuanling then set off and headed for Liaodong.

The crown prince Li Su felt sorry for his father Li Shimin and was worried that he would have a hard time fighting Goguryeo, so in addition to vigorously ensuring his logistics supply, he also tried every means to increase his troops.

After nearly 10 years of development, Datang has a strong national strength, and it can organize a strong military force by mobilizing it casually, just like now, mobilizing 200,000 people and materials basically has no impact on the local area. It not only replenished the Eastern Expeditionary Army, but also enabled the local government to participate in the imperial court war, which could enhance the patriotic consciousness of the people.

He was worried that Li Shimin would be unhappy, so he specially sent Fang Xuanling to meet Li Shimin.

After listening to Fang Xuanling's explanation, Li Shimin was also a little moved in his heart, and said: "Since this is the case, then stay." ”

Facts have proved that it is not superfluous to increase the strength of the Eastern Expeditionary Army this time.

With the centuries-old foundation of the Goguryeo Dynasty, the people have a strong sense of identification with the imperial court and are also determined to defend the country. Quangai Suwen urgently mobilized 700,000 troops throughout Goguryeo and deployed them near Pyongyang, and the biggest decisive battle since the founding of the Tang Dynasty was about to begin.