When Wei Yan heard Jia Xu say this, he suddenly remembered the hardships and slowness of marching in the past in windy and rainy weather.

Although this time to send troops to the Hetao, all the way is good weather, no rain and snow, dry soil, galloping on horseback, can still run, but the rescue is not only cavalry rescue, to first hold the city invincible position in order to pursue greater victory, elite infantry gallop speed to ensure that the speed of the horse, then to use carriages, of course, more importantly, the rear of the heavy grain, grass and ordnance to supply in time, these must be loaded by horse-drawn vehicles, so if you want to ensure the stability of the pass city in the Hetao area, To turn the Hetao into a strong rear and a stable granary for one's own conquests, it is necessary that the road leading to the Hetao can be smoothly navigated by horse-drawn carriages.

Wei Yan frowned and asked, "Wenhe, what are your plans to solve this problem?" ”

Jia Xu understood that the answer Wei Yan wanted was not a simple answer "build a road", but how to repair it.

Jia Xu had already made up his mind, and said without thinking: "Lord, why don't we rebuild Qin Zhidao?" ”

Wei Yan was a little unresponsive: "Straight? ”

Jia Xu pointed to the road that ran through the Qingyan Valley: "Well, that's the straight road." ”

Wei Yan looked at the avenue in front of him and asked curiously, "Isn't that a plank road?" ”

This avenue is all tamped with loess, flat, straight, wide, the widest place can drive twelve big cars side by side at the same time, if it is not paved with loess but paved with cement or asphalt, it is no different from the highway of later generations, and although this avenue is paved with loess, it is very hard to tamp, so that there is at most long grass on both sides of the road, not any shrubs, when it encounters rain and snow, it is only a thin layer of mud splashing on the surface, and most of the rainwater flows to the ditches on both sides, and it will not dip into the soil to make the road soft and difficult to walk.

Jia Xu smiled and said, "Lord, you have confused the plank road with the straight road. In order to pass the road in the deep mountain valley is smooth and unimpeded, they dig some holes with utensils on the cliff wall isolated by the river, and the hole ** is inserted with a wooden stake, and the wooden plank is laid horizontally, which can be pedestrianized and opened to traffic, which is called the plank road. The overhead passage between the high-rise pavilions is also known as the plank road, such as the Luoyang South Palace and the North Palace are connected by the plank road. The most well-known plank road is the Qin period built in Guanzhong to Shu four plank roads, Cai Ze once said, the plank road thousands of miles, through Shu Han, so that the world is afraid of Qin. ”

Wei Yan then remembered the famous allusion, "Ming Xiu Plank Road secretly crosses Chen Cang".

In 206 BC, Xiang Yu relied on his strong military strength to force Liu Bang, who had entered the Qin capital of Xianyang, to withdraw, and led his troops into it himself, and called him the overlord of Western Chu. Xiang Yu then made Liu Bang king of Han and let him rule over the remote Hanzhong and Bashu regions. At the same time, in order to prevent Liu Bang from re-entering the Guanzhong, Xiang Yu gave the rich Guanzhong to Zhang Han, a general of the Qin army. Liu Bang knew that his troops were inferior to Xiang Yu, so he had to swallow his anger. On the way to the fiefdom, he used Zhang Liang's strategy to burn all the plank roads that were hundreds of miles long, in order to show that he had no intention of returning to Guanzhong, so that Xiang Yu was unguarded against him. In August of the same year, some people rebelled. Liu Bang thinks this is a good time to send troops. The general Han Xin proposed a plan to repair the plank road and secretly cross Chen Cang, and suggested that someone should be sent to repair the plank road to confuse the enemy, Liu Bang adopted his suggestion and began to repair the plank road. The Qin general who guarded the pass, Zhang Han, ridiculed Liu Bang, and he didn't know what year and month he wanted to repair. In fact, Han Xin was secretly actively preparing for the attack on Chen Cang. Soon, Han Xin quickly dispatched troops and captured Chencang. Zhang Han panicked when he learned about it, but it was too late. Taking advantage of Chencang, Liu Bang's army soon attacked and occupied Guanzhong, laying the foundation for the later establishment of the Han Dynasty.

Wei Yan suddenly remembered that the straight road was a national defense road built by Qin Shi Huang in order to attack and defend against the Xiongnu, so that the general Meng Tian led hundreds of thousands of military and civilian workers to build a national defense road, starting from Ganquan Palace and ending in Jiuyuan County, 1,800 miles long, and the route was generally straight from north to south, because it was called "straight road" or "Qin straight road".

This is Qin Shi Huang annexed the Six Kingdoms, unified China, in addition to the unification of writing, currency, weights and measures and other political achievements, one of the two world-renowned events, one is to build the Great Wall, the other is to build a highway similar to the later generations - Qin Zhidao.

Qin straight road through the Loess Plateau in northern Shaanxi, more according to the mountain situation into the road, split the ridge for the road, the pass is wide, every ditch rammed to build, the straight road requires the road surface to be as straight as possible, so that the carriage and horses gallop quickly, the place passed, the terrain is more treacherous, and the human track is rare so far.

At its widest point, the straights can be traveled side by side by a hundred troikas, and its width is beyond the reach of any highway in later generations, making it the world's earliest, longest and widest super carriage road.

Wei Yan rode his horse along the straight road while listening to Jia Xu introduce the details of this Qin straight road.

In the fifth year of Qin Shi Huang's unification of the Six Kingdoms, in order to resist the powerful Xiongnu before Japan, he sent the general Meng Tian to lead an army of 300,000 to the north and expel the Xiongnu to the north of the Yinshan Mountains. The Qin army crossed the Yellow River, took control of the Gaoque fortress in the Yinshan Mountains, and established thirty-four county towns on the newly acquired land, and the people who migrated from the interior to these new counties to engage in farming, and in order to administer these new counties, a separate Jiuyuan County was established. At that time, the Xiongnu were in the period of power expansion, and would not give up the intention of invading to the south because of a temporary setback, Qin Shi Huang naturally understood the connotation, so in addition to setting up counties, migrating populations and other measures, he also built the Great Wall on the Yinshan Mountain Range, where there was the old site of the Great Wall of Zhao State, and it was relatively easy to process and repair. Does the construction of the Great Wall at this time mean a passive defensive strategy? No. Qin Shi Huang's strategy against the Xiongnu was not passive defense, but active defense, and the construction of the straight road is the best proof of this.

The straight road was built in the second year after the expulsion of the Xiongnu, the total length of 1,800 li, it was the most convenient road from Xianyang to Jiuyuan County at that time, if the Xiongnu dared to invade again, the reinforcements of the Qin Dynasty could follow the straight road from Xianyang to Jiuyuan County, and climb the Yinshan Mountain Range.

Qin Zhidao is a veritable ancient military highway, through this avenue, you can quickly transport a large number of strategic materials and troops needed for the northern border from the capital Xianyang to the northern military fortress.

Once there is a dangerous situation in the northern frontier, the cavalry troops can rush from Xianyang to Jiuyuan through the Qin Straight Road for three days and three nights, and they can basically complete a series of preparations from the army transfer to logistics supply within seven days, and the 1,800-mile-long straight road provides a fundamental guarantee for the Great Qin Empire to quickly put troops into the army, deliver grain and grass in time, and finally defeat the Xiongnu.

Wei Yan couldn't help but sigh: "If the Great Wall is like a shield that is blocking horizontally, then Qin Zhidao is a spear that pierces straight out; If the Great Wall is a bow that is drawn, then Qin Zhidao is an arrow that is about to fly out. ”

Jia Xu stroked his palms and smiled: "Lord, wonderful, your analogy is appropriate, Qin Shi Huang used a straight road to revitalize the entire defense posture, from the original passive defense to active defense, if it wasn't for Qin Shi Huang's early death, the Great Qin Empire would have wiped out the Huns a long time ago." ”

Jia Xu went on to explain the benefits of rebuilding the straight road, which will not only have the effect of military deterrence, but will also play an extremely beneficial role in the unification of government decrees between the north and the south, economic development, and cultural exchanges.

Jia Xu cites the story of the Qin and Han dynasties to illustrate that Qin Shi Huang immigrated to the north of the Wuding River on a large scale in the 33rd year (214 BC) and 36th year (211 BC), and in the second year of the Han Yuan Shuo (127 BC), the fourth year of Yuanzhan (119 BC), the fifth year (118 BC), and the second year of the First Yuan Dynasty (85 BC), the military tun and the min tun were also implemented in Shuofang four times. The Qin and Western Han dynasties implemented these immigration measures, all relying on the straight and galloping roads from Xianyang and Chang'an to Shangjun. After Juntun and Mintun, the areas inside and outside the Great Wall, which were originally based on "animal husbandry as the world's rao", were called "Rao Valley" and "many livestock", and changed from the original animal husbandry area to a semi-agricultural and semi-pastoral area. At that time, the population of Shangjun was more than 600,000, which was more than the developed Hanzhong County.

Jia Xu smiled and said, "My lord, if you want the people of other states and counties to develop the Hetao faster, you'd better rebuild the straight road." ”

Wei Yan ascended high and overlooked, the straight Qin straight road has been vertical and horizontal to the south, if like a yellow dragon, Wei Yan looked back to the north, the Great Wall on the Yin Mountain is like a dragon, the Great Wall, the straight road if the two dragons are closely coordinated, will be able to restrain the Saiwai Hu people to the Han border prying eyes, how can the Eastern Han Dynasty court be different from the Western Han court, there are many family ministers to control, but also use more passive defense, after giving up the Great Wall and the Yellow River, the straight road has become an ordinary road, and it has been in disrepair for a long time, the road is overgrown with grass on both sides, and some places begin to collapse.

Jia Xu's introduction to the straight road made Wei Yan have the ambition to chase after the Qin Emperor far away.

Jia Xu said again: "Lord, as for the Hetao and Yiyang, limited to Taihang, Luliang blocking the road, we can not build a straight road, but we can build a straight road, the gallop road is connected with the straight road, along the gallop road soldiers and horses to the Hetao, along the straight road, the north can hit Xianbei." ”

Although Wei Yan himself is quite literate, he only knows a little more about the history between the Three Kingdoms, and he doesn't know some things between the Qin and Han dynasties, while Jia Xu is not only quite resourceful, but also a well-read person, and the sons of the pre-Qin Dynasty know everything, so he can put forward a ruthless move in military and political terms.

After Jia Xu's introduction, Wei Yan had a deep understanding of Chidao, and he suddenly found that the straight road was like the highway of later generations, and the Chidao was like the railway of later generations.

In the second year after Qin Shi Huang unified the six countries, he ordered the construction of a gallop road centered on Xianyang and leading to all parts of the country.

Chi Road is the emperor's special lane, and the ministers, people, and even relatives of the emperor have no right to walk. The road is in a flat place, the road is fifty steps wide, a tree is planted every three zhang, the two sides of the road are rammed with metal cones to build thick, and the middle of the road is the part dedicated to the emperor's patrol car.

Jia Xu was good at meeting the wishes of the people, and naturally understood that Wei Yan was a very pragmatic master, not like Qin Shi Huang, so he smiled and said: "This Qin Chidao can be used for military purposes, to transport military supplies, to transport infantry to the front." ”

Jia Xu led the way in front and led Wei Yan to a gallop road.

Wei Yanfei dismounted, came to the gallop that was already a little broken, squatted down, and carefully observed the construction of the gallop road.

Wei Yan took a closer look, and this galloping road, which had long been abandoned in the Eastern Han Dynasty, actually surpassed the advancement of this era.

This Qin Chi Road is an ancient "track", the principle is no different from that of modern railways, it is also a double line, but it is not a train pulled by a steam locomotive, but a carriage pulled by horsepower; Paving on both sides of the road is not the railroad track, but the wood, the wood material of the track is hard, and after anti-corrosion treatment, although after more than 400 years of wind and rain, so far intact, but the sleeper has been decayed, obviously not after anti-corrosion treatment, the material is not as hard as the track wood, but it can also be seen its general appearance. The roadbed is rammed very strongly, and the sleepers are laid on the roadbed.

Jia Xu picked up a sleeper and handed it to Wei Yan: "Lord, you see, this sleeper is relatively soft, not only to reduce the workload, nor only to open up a wide range of timber sources, but the craftsmen of the Qin period consciously selected, the softer sleeper can be closely combined with the rammed very hard roadbed, so that the track is stable, and the car can run quickly and smoothly on it." ”

Wei Yan smiled and nodded, he felt more and more that many good things in the Qin Dynasty were abandoned by the Han Dynasty, and it was worth picking up those good things by himself, such as straight roads, such as galloping roads, such as the standardization of weapon production, in the Qin Dynasty, the military industry has been very developed and scientific, and has achieved standardization, serialization and generalization, the craftsmen of the Qin State make sixteen million identical arrows every year, and the crossbows they manufacture are exactly the same as modern rifles, and even the appearance of the parts is completely similar to that of rifles, Moreover, its production is also standardized, serialized and generalized, and any part can be installed by picking it up.

Jia Xu smiled again: "Lord, you see that the distance between the sleepers of this gallop is just the right distance, and it is said that it is just in line with the horse's steps." Once the horse is on the track, it can't help but run fast and can barely stop. Every thirty or forty miles, there is a horse station, and the people at the horse station fill the wood between the sleepers to level it, and there are many horses waiting here, all of them are fed there, and they are well rested, and once necessary, they can gallop on the cart, and the horses will not stop, and when they reach the next horse station, because the sleepers have been filled and leveled, the horses can gradually slow down and stop, and replace them with another well-fed and rested horse, and continue to gallop forward, so that they can reach a very fast speed. This was the most economical use of horsepower, and it was said to reach at least a thousand miles in a day and a night, which was faster than a cavalry gallop. ”

Wei Yan's eyes widened when he heard that he could reach such a speed on the gallop road, which was far beyond the technological level of this era: "It is no wonder that Qin Shi Huang can effectively manage a huge empire without dividing the feuds, and he can often carry out large-scale operations of hundreds of thousands of people. ”

Jia Xu said again: "My lord, you have strongly advocated four-wheeled carriages before, which are more stable and heavier than two-wheeled carriages, and are especially suitable for running on galloping roads. The ride is smooth, there is less friction between the ride and the wheels, and the horse-drawn carriage is less strenuous to pull up the carriage, allowing more people or more goods to be pulled at a time. ”