The three armed forces have not moved, and the grain and grass will go first, which means that before sending troops, the grain and grass will start ahead of time. Be prepared before you do something.

From Nanpi county annals, local chronicles and ballads: the soldiers and horses have not moved, and the food and grass go first. Apologize every year and guard against thieves every night.

In war, especially in important battles, tens of thousands, even hundreds of thousands and millions of troops are often used. Under this scale, soldiers in the army should make preparations for food, clothing, housing and transportation in advance, and they don't have to declare war today, but they will be ready tomorrow, which usually takes a long time. In addition, it is necessary to predict the prolongation of the war and even the transportation of grain and grass for a long time. You know, a car full of food should also be equipped with a corresponding number of people to transport, and these people also need food and shelter. Logistics support for combat readiness is not a simple matter. This has produced the saying that "grain and grass come first".