Ice is not widely used in the ancient battlefield is actually not widely used, mainly because it is believed that the ancient battlefield is dominated by the Central Plains, and the temperature in the Central Plains is not particularly low even in the cold winter of Layue, and the low temperature attribute of ice has not been effectively brought into play.

Yang Yanzhao once mobilized soldiers and civilians in a certain place in Jizhou to brave the severe cold, draw water to irrigate the city, pour water on the city wall, and use the ice city to resist the attack of the Liao State. In the face of the Liao army that Empress Dowager Xiao personally came to the city to beat drums and supervise the battle, Yang Yanzhao seized the opportunity of the arrival of the cold wave that was rare in a century, and ordered the soldiers and civilians to water the city wall again and again, and freeze again and again. Although the Liao army reluctantly launched a general attack, but the arrow shot on the ice wall at most left only a white spot, the ladder can not be set up on the smooth ice wall, will slide left and right, and will easily be pushed down by the Song army defending the city, and the soldiers who have talked about it can not climb the siege, the Liao army dragged on under the city for several days, and the weather did not improve, so in desperation, they had to retreat.

Here is going to be a popular science, junior high school physics everyone has learned, water freezes at about 0, but at different temperatures, the hardness of ice is not the same, the lower the temperature, the greater the hardness of ice, at 0, the hardness of ice is 1-2, it is easy to break, and the glass that has not been tempered, at minus -15, the hardness of ice is 2-3, at this time, its hardness is basically the same as pure copper, and when the temperature drops to minus -40, the hardness of ice will become 4, which is equivalent to the hardness of steel, if it goes down, At -50, the hardness rises to 6, which is more than steel, and at -70, ice can reach 7, which is harder than granite.

From water to ice, the volume will increase somewhat, but continue to cool, and it will conform to the principle of thermal expansion and cold contraction, ice as the temperature decreases, the volume decreases, the ice is stronger, the hardness will also increase, in the case of ultra-low temperature, ice may be harder than steel, granite.

Now I estimate that the outdoor temperature must exceed -30, the ice between the city gates, close to the hardness of steel, and the water prepared for me by Dongfang Lonely Bai is very sufficient, which can fill the gap between the city gates about one meter longitudinally, generally speaking, a certain thickness of ice, at a relatively low temperature, can resist bullets and even cannonballs, for example, at -25, the ice becomes very hard, and it can be used as "armor" in war, the performance is not inferior to my soft hedgehog armor, and it is very light.

If it is outdoors in the extremely cold winter, in the water, wood chips or fibers are added to freeze, it will greatly increase the strength of the ice, and the protection effect is better. During World War II, the Allies mixed the wood fiber with water and froze together, so that the wood fiber formed an anti-ice melting isolation layer, this fiber reinforced ice is extremely solid, the thickness of only 2.5 cm of large ice plate, can withstand the weight of 6 people, 10 cm thick large ice plate, can resist pistols and foot ***, so that the Allies in the battle against the army casualties greatly reduced.

Now the ice on this side of the city gate is one meter thick, not to mention that the rebels' thermal weapons are not easy to use, even if Dai Lu's cannon is pushed over, it may not be able to blast open.

I really admire Dongfang Lonely's execution ability, the Xiaoice Mountain at the drainage exit, how did she open it in a short period of time? It is estimated that the locals must have a unique way to deal with freezing, it is definitely not a hard chisel, it is as hard as iron, how to chisel with an iron chisel? It is estimated that it is to use fire or the like, heat it, let the iceberg melt, or raise the temperature, and then find a way to chisel it.

Of course, if you want to use soldiers to defend the city gate, you can't rely on hardness alone, but also have toughness, coincidentally, ice really has a large tensile strength, compressive strength and bearing capacity, according to scientific experiments, the tensile strength of low-temperature ice is extremely large, up to 12 kg - 15 kg per square centimeter, and the compressive strength is 35 kg - 45 kg per square centimeter. As the temperature gets lower and lower, the thicker the ice, the stronger the bearing capacity, and on top of half a meter of ice, you can drive dozens of tons of tanks over.

Therefore, no matter whether the rebels hit the door with a battering ram or pull it with a horse, it is useless, they can't open it, they can only find a way to melt the ice between the gates, but that will take time!

That's what I'm going to fight for!