In ancient times, people went out to kill people and sacrifice flags. How to sacrifice them?

An ancient superstitious practice: before going out to war, the army leader killed a living creature and sacrificed his life to the gods in order to seek their protection.

This is very old.

Later, the beheading flag was widely used in the military, which was recorded in Spring and Autumn Annals, Book of Rites and Historical Records. It was in a very old war. The exact time cannot be verified.

There is another meaning: boost morale. Make an example of others. Effect.