In books and on TV, we often see the saying that the ancient war has retreated. China's ancient concept of "five elements" holds that the world consists of Jin Mu, fire, water, earth and, fire, water and earth, which respectively correspond to the five directions of "southwest, northeast and south". Gold means metal. In the "five elements", the corresponding position of gold is the west, and the west symbolizes convergence. Convergence means no more attacks. Therefore, the ancients used "ringing gold" to indicate the signal to stop attacking and end fighting.
"Jin" is a bronze musical instrument called "Ju", which was called "Jin" in ancient times. It is shaped like a clock, but it is longer and narrower than the clock. It has a handle on it and can be hung. In ancient wars, once the pheasant was shot down, it meant that the battle was over and both sides retreated. Judging from the actual situation of the battlefield, the ancients' "beating drums to March, ringing gold to retreat" contains certain scientific principles: drums are made of leather, and when they are struck, the sound is rich and shocking, which can play an inspiring role; The sound of knocking on metal is crisp, penetrating and far away, which is convenient for soldiers to hear the withdrawal signal clearly.
In the Northern Wei Dynasty, it was found that the gong was flat and round in shape, and it sounded loud when struck, which was stronger than the penetration of a pheasant. So the pheasant was gradually replaced by gong, and the "golden bell jar" gradually evolved into "gong".
After entering modern times, no matter beating gongs and drums or beating gold, they no longer meet the needs of large-scale wars. The signals of attack and retreat have also changed accordingly, such as blowing horns and launching tracer bullets. In modern high-tech war, the war signal can even be an electronic command. The only constant is that the signal of war is the unified dispatch of troops. Military orders are like mountains, and the army must ban them, otherwise it will be just a mob.