There is a classic line in the movie "The Great Cause of Building the Army": "Since ancient times, the military has been used, and the military has been divided into three parts and the economy has been divided into seven parts." In a war, the deployment of generals and the combat effectiveness of soldiers are not as important as strong economic support. Hitler aimed the butcher's knife at the Jews in World War II, not only because Hitler was a loyal anti-believer, but also because he wanted the amazing wealth that the Jews had. In the end, Nazi Germany was defeated by the economic collapse because of the long-term stalemate with the Soviet Union in Eastern Europe.

So where is the most expensive place in the war? Whether in the era of hot weapons or cold weapons, soldiers' wages and pensions for fallen soldiers are the bulk of expenditures, but they are not the biggest expenditure items. In the era of hot weapons, the economy will be mainly used for the loss of weapons and ammunition and the research and development of advanced weapons, while in the era of cold weapons, the allocation of grain and grass is the most economical expenditure item.

There is a famous saying about war in our country, which is called "the soldiers and horses did not move food and grass first." Because the war in the era of cold weapons can't end in a short time, the siege will probably last longer. The hay at this time represents the inside information of the warring parties and the time they can persist. At that time, soldiers had to go to war hungry, not to mention reducing the combat effectiveness of the army. It was good for soldiers not to defect. So in ancient times, fighting for food and grass was a top priority.

But during daily patrols or drills, soldiers also have to eat every day. Why did you find that there was not enough food in the war? Many people think that soldiers need more food for every meal in battle than usual. This was indeed one of the reasons for the food shortage during the war, but it was not the main reason.

In ancient times, people did not have mechanical tools to help them cultivate, but farmers planted crops artificially, and no chemical fertilizer could improve the fertility of cultivated land. The productivity of this kind of work is very low. Peace is good, and money is short immediately in war. And if it is a large-scale battle, the court will send a large number of young people to the battlefield after emergency training. As a result, there are naturally not many people engaged in farming in farmland, and the grain productivity has dropped again.

In addition to productivity, there is also a weakness: the ancient mode of transportation. During World War I and World War II, food supplies were transported by plane or train, which was not only fast, but also without too many restrictions. In ancient times, food could only be transported by carriage. Not to mention the slow speed, but also vulnerable to the weather and terrain, the enemy will send people to cut off the supply line.

Sun Tzu's Art of War says that "the country is poor, but its teachers are far away", which means that the country has declined because of war, mainly because of long-distance transportation. It is considered that in the process of transportation, "autumn trains, ten to six." After long-distance transportation, including the loss of people, cars, horses and other resources on the way, ten kinds of resources have consumed six points. So how did the excellent generals in ancient times avoid the shortage of food and grass? "The Art of War" also gives the answer, that is, "take it for the country, because food is the enemy, and military food is sufficient." Sun Wu believes that excellent generals will get food and other materials from the enemy to enrich themselves when they conquer the enemy's territory, so as to achieve the purpose of preparing for war and maintain the combat effectiveness of the army to the maximum extent.