Baili Yan (Wei Xian) smelled the smell familiar:

"Shhh...... Isn't this the smell of rubber, could it be that this black smoke was pulled out after igniting the rubber? ”

Bai Liyan was sure that what Yuke ignited must be rubber, and only rubber can emit this kind of black smoke. It can not only create a smoke screen to interfere with the sight of the Flying Eagle Beast, but also indirectly kill the Flying Eagle Beast to a certain extent by releasing toxic and harmful gases.

The source of rubber, the most likely should be Changsun country, rubber trees can only grow in the tropical warm and humid rainy season, Xianguo is located in the subtropical low latitude of the North Sea, but has never seen rubber trees, only the northernmost counties of Changsun country are located near the equator, rubber trees are most likely to come from there.

This reminded Bai Liyan of the book "The Narrative of Miscellaneous Workers of All Things" that he saw in his early years, which recorded: There are milk trees in the hot north, the holy white fragrance is fragrant, and after drying, it is soft like fleshy skin, and the glutinous bullet is endless.

At the time, I didn't understand what the bottom was, but now that I think about it, it must be a solid substance after the solidification of rubber juice.

However, when you think about it, there is almost no industrial chemical demand for rubber nowadays, and there has never been a trade in rubber for trade varieties, let alone in the military field. Because the gas particles after rubber combustion are not like burning wolf smoke, sulfur and other substances, they are dispersed and floated on the ground in all directions, and the particle pollutants produced by rubber are small in density and light, and most of them rush directly to the sky, and the number of natural residual toxic gases is small, and it cannot quickly kill people in a short time.

Even so, within a radius of 25 square kilometers of Tiannan Pass, thick smoke billowed everywhere, and there were no less than 200 ignitions, and the pungent gas produced by the rubber was easily obstructed by the city wall.

In order to prevent toxic and harmful gases from accumulating in the city, there are earthen platforms that are more than 10 meters high and more than 20 meters high are built everywhere in the city, and copper pots are put on the earthen platforms to produce thick smoke by putting naturally solidified rubber blocks, which is more conducive to the rapid diffusion of most toxic and pungent gases.

At the beginning of this day, the barbarian army took turns to attack Nantianguan 24 hours a day, and at the same time, several stone machines, more than 20 giant counterweight trebuchets with a range of more than two miles, under the traction of mammoths, pulled to two and a half miles outside Tiannan City, and began an endless bombardment on the south gate city wall, the huge stones were more sensational than the largest stone pills seen before, falling to the ground higher than adults, and the pouring force of the city wall reached unprecedented destruction.

The Xianjun once hung grass and mud bags on the city wall and strengthened the city wall, but in motion, hundreds of catties, one or two thousand catties of boulder face, how insignificant, any huge tilt on the city wall, let alone a pit half a meter deep.

In the middle of September, the grassland began to rain, the light rain continued to flow, Zhao, Chen, Qi, Yan four famous generals arrived one after another, Tiannan Pass had 80,000 troops, Qi Guo by Zhennan General Ji Yao led 20,000 troops.

Due to the small size and widowhood of the country, the general only set up the post of general of Zhennan, and even the post of general of Zhengnan was hindered by the prestige of defending the country. Therefore, General Zhennan is the only permanent general in the active service of Qiguo, and if Ji Yao is not a close confidant of King Baililu, he will definitely not be able to do the post of general.

Ji Yao's record is mediocre, Lu Ye's strategy has a performance, at best, he has a record in Qiguo, looking at the entire Central Plains, Ji Yao is ranked outside the forty, and even the records of some major governors are not comparable, not to mention what a famous general.

On the twenty-third day of September, the temperature dropped rapidly, and the ground froze for the first time on the twenty-fourth day of September, and the first snow fell on the second day of October. Jiang Jie and the others are all from Xianguo, they have never seen snow in their lives, and at first glance they see snow flying outside the sky, like a magic skill, but Bailiyan can't help but be happy.

Jin Xuedi has been bombarding the South Gate for more than 20 days, and Cao Chizheng has held seven military opportunities to discuss the defense strategy for this winter.

There was a suspicion before that Yuke summoned famous generals from various countries to help in the war, mostly to establish a staff organization, but now it seems that Cao Chizheng is in high esteem. It is not so much the establishment of a staff organization as the hostage pledged by the vassal states in the hands of the royal guests.

As the saying goes: A thousand troops are easy to get, and one will be hard to find.

If something happens to the general, the blow to a country's army will undoubtedly be devastating. In this way, if some accidents occur to the famous generals of any country, the combat power in the future will undoubtedly be greatly reduced, because talents are scarce, and there are no talents like Bailiyan.

The military opportunity once again asked the vassal states to send troops and horses south, focusing on the Jin State and the Wei State. As the only two major countries that were not directly involved in the Black Turban Rebellion, the number of standing troops in the army was more than five or six hundred thousand, and even if the main force was not drawn and conscripted to participate in the war, the number was also very large.

The snow fell for seven or eight days one after another, and in the middle of October, it snowed four swans in a row, and the snow was not up to the knees, and there were only more than 40 people in the Xianjun camp alone.

Gongjiang is nearly 4,000 miles away from Tiannan Pass, and the Southern Expeditionary Army has 30,000 people and countless horses and horses, and they can't walk much every day. Bailiyan didn't force a deadline, but just asked Sikong Nan to arrive as soon as possible.

Previously, it was estimated that two months on the road should be enough, and it should be able to arrive at the end of October and early November, but at the end of October, the road was closed by heavy snow, and Baili Yan's heart sank to the bottom, and Sikong Nan was most likely trapped on the road.

Jin Xuedi's air raids and stone attacks continued day and night, and the city head suffered great casualties every day, and the coalition army also had long-range trebuchets that relied on animal power and counterweight levers under the south gate, so what could it be, the range was not as good as the barbarian army's trebuchet and giant trebuchet, and the barbarian army completely hid outside the range to launch an attack, and the coalition army was powerless.

After winter, the ground became hard, and Bailiyan organized Jiang Jie and more than 40 guards to dig field fortifications and cat ear holes on the spot in the Xianjun camp.

In the previous military battalion, Bailiyan had begun to popularize the construction and excavation of field fortifications, as well as cat's ear holes, underground bunkers, communication trenches, etc., which could effectively resist the attack of stones and arrows, and at the same time serve as a position for resistance and ambush, delaying the enemy soldiers entering the city.

This time, the Southern Expeditionary Army was equipped with a lot of new quenched steel short-handled shovels, both sapper shovels, and cross pickaxes. When not in use, use a rope buckle to fix it on the back armor or outside the backpack, untie the rope buckle slipknot on the chest when you use it, and remove the baggage shovel and pickaxe, which can be used as a secondary weapon or arm shield. It not only increases the back defense, but also makes it easy to carry.

After hundreds of years of expansion and construction, Tiannan Pass has underground bunkers, hidden soldier caves, and tunnels all over the city, even so, it is impossible for more than 200,000 troops, more than 100,000 people, and 100,000 war horses to hide all in bunkers.

The fortifications were excavated from the day of the snow in early October, initially taking advantage of the gap between air raids and at night.

Eagle Beast air strikes day and night, attacking visible moving targets in the city, and air raids at night with visible light. Therefore, the fire in the city at night is either underground, or the doors and windows are covered, which can be regarded as the prototype of light control.

More than 40 people dug until the beginning of November when the snow covered the mountain, the snow on the ground was knee-deep, the thickness of the excavated soil was two meters, and the depth of the bunkers was one and a half feet underground. There are more than 200 deep and shallow cat ear holes, three command rooms of 10 square meters, and two layers of earth bags on the surface.

On November 17, the snow was heavy and the world was dripping into ice, and the barbarian army continued the monotonous and tedious rhythm of air raids and bombardments, and occasionally there was news that the two cities of Xu Tu and Duhui were attacked.

After Cao Chizheng held a military opportunity four days ago to report the latest information, there has been no other follow-up. However, the vassal states sent many military attaches to observe the bunkers dug by the Xian army, and then they remembered that the armies were fighting for the Tibetan soldiers all day long, so it was better to dig them themselves.

The barbarian army bombarded the city every day, but did not attack, Bailiyan and more than 40 people hid underground every day, except for one or two trips to patrol the city every day, most of the time they shrank and the underground cat winter.

One day, Baili Yanxing killed two sheep on a bloody whim, washed and peeled them and hung them outside the world, froze them hard, sliced them and made a hot pot. The southern border is located on the plateau with low air pressure, there is no pressure cooker, the water cannot be boiled, and the food is not cooked for a long time.

The bunker was steaming and smelly, and more than a dozen people gathered around a copper pot, soaking mutton while dipping it in the hard-to-get soy sauce while eating and talking.

"My lord, this mutton is really tender and delicious, and it cooks much faster than the mutton cooked in the pot. If this is known to the other princes, they will not envy them to death. Jiang Jie said while eating, with a look of shame on his face.

"Envy is still to come, it's just a little clever at best. Ben will ponder, Jin Xuedi has been delaying the siege of the city, most of the time there is nothing good, September suffered such a big loss, and it is not a good phenomenon to see the snow in the past two months. I've been eating and drinking for the past few days, and I'm going to have a big event. ”

"My lord, yesterday my subordinates went to the south of the city and walked around, and the outer edge of the city wall was like a dog gnawing, and it didn't collapse, so my lord said it was strange."

"Actually, there is nothing surprising, at the beginning of the construction of the city wall, the soil was added with bauxite and quicklime, and when it was heated by water, it was like firing pottery, which was extremely hard and tough. In addition, for hundreds of years, the price of glutinous rice in Xianguo will increase several times whenever the war in the south is calm, in fact, it is used to repair the city wall in Qianyue Mountain, so every city in the south is impregnable. If this is moved to the Central Plains, it will not be able to be attacked at all. ”

"According to what my lord said, this city is still very precious."

"You can settle accounts, and your words are really good, it is precisely because of the preciousness that the city of Qianyue Mountain can not be built in a year or two, and it has been continuously repaired and expanded for hundreds of years to have such a scale as it is today."

Qin Shi Huang repaired the Great Wall, is to Yan, Qi, Zhao, Qin four countries of the Great Wall connection, by no means a day's work, even so, the Great Wall of Qin has only been repaired for more than ten years, barely connected the Long March, after the continuous improvement of the Han Dynasty and the maintenance of the dynasties, there is the Great Wall of the Ming and Qing Dynasties.

Qianyue Mountain is located on the plateau, oxygen is scarce, and Bailiyan has also thought about why not build a Great Wall near the city of Zhuchi, so as to isolate the inside and outside of the pass. But in this way, the 2,500,600 miles of land south of the city will be ceded to Jin Xuedi, and Jin Xuedi will also establish a huge advance base at the doorstep of the Central Plains vassal states.

If the Great Wall is built on the plateau, the current technical conditions and productivity do not allow it, and I don't know how many manpower will be killed or injured. On the contrary, it is obviously more cost-effective to seize the land available for subsistence on the plateau to build fortified cities.