Why did the drums only beat three times in ancient times?

This is a traditional etiquette in war. After the establishment of the system of rites and music in the Zhou Dynasty, the ancients often put etiquette first. Therefore, there is a saying that "there are no more than three things", and then the three drums in the war became written law. Generally speaking, if troops have not been sent after the three drums, basically this battle will not go on, and morale will be "exhausted." Later, because the system of the Zhou Dynasty was abandoned during the Spring and Autumn Period and the Warring States Period, people did not observe rites and music, so the other side attacked and won after the three links.